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How To Mint NFT Art For Free At Opensea

David has been an enthusiastic adopter of NFT art and created and sold NFT artworks on various different cryptocurrency chains.

Introduction To Minting At Opensea

NFTs have become increasingly popular as a means of selling and buying digital based artworks. Since late 2020 what was first a niche sector of the cryptocurrency world has blossomed into a widespread platform for artists to sell and promote their work. With Beeple's $6m sale of his NFT work and various artists and celebrities launching their own NFTs, this form is rapidly becoming a mainstream concept.

As an artist, if you want to get in on it, it can be a steep learning curve. You may want to try selling your work as an NFT, and there's a lot you'll need to learn first, from cryptocurrency wallets, creating a suitable work to turn into an NFT and minting and promoting the work. I could spend a whole day just covering the basics, but that is best done elsewhere. Instead, what I'll do with this guide is show you how to mint on Opensea, one of the world's biggest NFT marketplaces.

What You'll Need To Mint At Opensea

Firstly, you'll need a completed artwork ready to place up for sale as an NFT. Typically this will be either an image, sound or video file that you've created as the finished artwork. There are also various other formats that are used for NFTs, such as 3D files and generative code, however, we will just stay with the basics here in this guide and upload an image file. The process is the same for the other kinds of files, so you can still use this guide if you've not done it before.

The first and most important thing you'll need is an Ethereum wallet. Ethereum (or Eth as it's listed from now on) is one of the more popular cryptocurrencies used for NFTs. There are others with vibrant NFT marketplaces on them, but Opensea is primarily Eth powered. This means you will need an Eth compatible wallet, I personally use Metamask, and that's what I've used on this guide as it's not only one of the easiest to use Eth wallets, but it's also the most widely available.

You don't need Eth loaded in the wallet, but if you want some, you can purchase it directly from Metamask, which saves you setting up an account with an exchange. A word of advice about using Metamask - never provide anyone the secret key you are given when you set up your wallet. There are people who are actively trying to scam the private key out of people as it gives them a chance to take over the wallet and steal your Eth. Never, never share it with anyone, and keep your seed phrase in a safe place.

The other thing you'll need is your artwork in a digital format ready to go. How you got there is up to you and part of the fun of NFT art. It’s now free to mint at Opensea, as they use a process called ‘lazy minting’ – this means you will not incur any fees until an item actually sells, then the minting fees will be deducted from the final sale price.

Let's Get Minting At Opensea


1 - Connect Your Wallet

First off, visit Opensea’s homepage to start. Click on the wallet icon in the top-right corner to be offered a choice of the wallets you can sign in with and connect to your account. Your wallet address is attached to your profile page as the login for the site.


Select your wallet, in this case Metamask. A window pops open with your Metamask accounts, make-sure you have the wallet address you wish to use on the site selected. Click next in the wallet window, and you will be prompted to sign to connect your site and Opensea.


Once you’ve connected, you’ll see any balance in your wallet. You will also be able to access your profile page, which you can customise with an avatar and background image.


2 - Create A Collection

Now your wallet is connected, you can begin to mint. Before you mint you need to create a collection where your items will live. The collection is a separate entity to your profile, so you could style it or brand it differently. You may want to keep the same avatars and background as it reflects your brand.

You can have multiple collections if you want, each branded differently – ie. My Paintings, My 3D Art, etc. Most people are happy with just the one though, so no pressure! Here’s where you go to start minting. Click the profile icon then select My Collections.


The next step is easy, select Create A Collection to begin. The three dots give you options to export contracts from other marketplaces, but that’s beyond the scope of what we are doing here, so ignore it for now.

Scroll to Continue

Once you’ve pressed create, you will get a pop-up window with the details you need to fill in. It’s self explanatory, Logo is the avatar that will show for your collection, Name is the name of the collection, i.e. My Art, Artist’s Name, Art By Me, etc. You can use the description box to give your collection some background information.


Once you’ve filled in the details, and you’re happy, press the create button. You’ll know you’ve succeeded as you will get a pop-up telling you so. Now you’re ready to start adding items. You can create your first item from here with the Add Items button or by going back to your profile and starting from there.


3. Mint Your First Item – Single Edition

It’s not really minting yet, you’re just listing your item as available. Technically, it will only really become an NFT when it is purchased. The Blockchain part of the equation doesn’t happen until the transactions take place. This is done to keep the price down for those listing and to avoid overloading the blockchain. It does have a downside in that people can quickly throw any old stuff up for sale, but the fact it’s free is also good for an artist’s wallet.

The first thing you need to do is to add an item. Whether you go from the pop-up when you create your collection, or go from the collection page itself, the first thing you will be asked is to sign. This is your wallet giving Opensea permission to create an item on your wallet address. You need to accept the request to sign.


The next thing you will do is create your first item for sale. We’re working on the model of a single item. Currently doing multiple editions requires an additional little step that we will look at later in this guide. Once you’ve signed the request to create an item, it’s fairly self-explanatory. The upload box is the item you are selling, you can see the accepted formats and file size restriction below. Currently, your file cannot be bigger than 40mb.

The name field is the title of your artwork. This is a required part of the process, so if your work is untitled, you can call it Untitled. If you don’t give it a name, you won’t be able to complete the process. The other fields are optional. You can link to an external webpage if you’d like, with info on the piece or your portfolio. The description is the place where you can talk about your work and what’s behind it.


Carrying on down the Create Item options, the next fields can be a bit confusing and counter-intuitive. You can add various attributes to your work via the Properties fields. Properties could be any number of things you think are needed to describe your piece beyond the description. So, it could be Colour – Black, Size – 30mb, Format – Jpeg, etc.


One property that you definitely should consider is tags. Tags work like hashtags in Twitter or Instagram, in that they can be clicked to list items with the same tags. There is not a tag field as such, it is something you need to add as part of the item’s properties. In the example below, you can see I have typed in Tag as the type, and then the Tag itself in the name field. Then at the bottom are additional properties that I have created, Size and Format. You type these in yourself, there is no way to select them other than creating them yourself.


The other fields, Levels and Stats can generally be ignored if you don’t feel you need them, they tend to be game and non-art collectible related fields. If you are creating a limited edition, you could use the stats field and have Edition as the first field and the number of the edition as the second, but again it’s optional.

Hidden Content can be used if you want to add a secret message or content that only the buyer can access. They will access it via the website page once they’ve bought the item. Not Safe For Work should be selected if your piece is not, well, safe for work… The Supply option is greyed out and cannot be used on a single item. It takes a little URL hack to make this work, which we will look at shortly.

Once you’ve filled in all the forms, press the Create button, and you’ve just created your first item for sale as an NFT. This will now show up on your collection page. The item is not yet ready to be sold though, you will have to list the item for sale, which we will do after this brief detour for if you need to create an item with multiple copies.

4 - Mint An Item With Multiple Editions

You might want to sell your item as a limited edition piece, available to multiple buyers. This is possible on Opensea, but it requires an additional step to unlock the ability to create an edition of an item. The beginning is the same, you’ll go to Add Item and be taken to the Create Item Page. Now, before you proceed, you will need to add an extra bit to the URL in the browser’s address bar.

Add this to the end of the URL – ?enable_supply=true

The URL will look like this with the bit you’ve added on the end.


Once you’ve typed or pasted in the additional bit of the URL, press the enter button and the page will reload. Look down the options and the Supply field is now editable. If you want to create an edition of 10 pieces available to sell, this is where you set the addition size. The rest of the process is the same as above, so just fill in all the boxes and properties you require and create the item.


You will see that you have been successful in creating multiple copies once the item page appears, it will show the number created in the item page and show them as owned by you. In the below example, I created an edition of 3 items.


With your item created, whether a single or multiple edition piece, you’ll want to move on to the next step, listing your item for sale.

5 - List Your NFT For Sale

Now that your item is created and sitting in your collection, it’s time to put it up for sale. If you open the item’s page, you should now see the option to Sell.


Once you click the Sell button, you’ll go through to the sales page, and you will have to decide which kind of sale you want to make – a fixed fee sale or an auction style sale or to sell the item as part of a bundle. For here, we’ll with go with a fixed price sale, but it’s equally straightforward for an auction sale. If you want to sell multiple different NFTs as one lot, that’s what the bundle feature does (but we’ll not cover it here.)


It’s all self-explanatory – Price is what you want to sell it for. If it’s an auction, you’ll need to use starting price and include ending price. You can choose to schedule for a future date and time, and use privacy if you don’t want the sale to be public and only open to a specific buyer. You can adjust the fee level for any affiliates, should you wish to change it (you might have spoken to an affiliate who is going to promote it for you and you want to make it worth their while.)

When you’re happy with your price and the other features, hit the Post Your Listing button and the sale begins. You will be prompted to approve the sale in your wallet. With Metamask a window pops up, and you press the Sign button to approve the sale listing.


It’ll will take a few seconds and that’s it, the item is available for sale now. You should see your item page with the price you set now live on the page.


And that’s it! Your item is now available for a buyer to purchase. Don’t forget, there will be fees attached to the sale as it is purchased. If the buyer makes you a lower offer that you accept, you will have to pay fees towards the minting process. Opensea will also take a cut, and there may be a cut if the seller was referred to the page by an affiliate.

You can also lower the price if you want, just click the Lower Price button and put your new price in the pop-up window and approve it. There’s one last thing we’ll cover, before we leave, and that’s what to do to cancel an item that you’ve put up for sale.

6. Cancelling A Sales Listing

Hopefully, this is not something you’ll need to do, but we’ll include it here, for reference. There could be any number of reasons why would cancel a sale, such as it features incorrect information, or you’ve decided to move the item to another platform. Thankfully, it’s nice and easy to do, but be aware, it does come at a cost. Locate the button to cancel your listing on the item’s page as below.


Click the Cancel Listing button, you’ll get a confirmation prompt from Opensea warning that a transaction is required to cancel the listing. Approve the cancellation and your Metamask will spring to life, popping up a window to confirm the transaction. As you can see, there is a small gas cost fee to cover the cancellation, this will fluctuate based on the current price of Eth and how busy the network is. Once you click confirm, there item will be cancelled.


And that’s it, your item is no longer listed for sale on Opensea.

And Finally…

Opensea is the easiest place to get started as an artist offering NFTs. It’s not got the status of sites like Foundation or SuperRare and their ilk, but as a place to try, it’s a good place to start.

This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.

© 2022 David Lloyd

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