Mint (and buy) NFTs with NO Gas Fees! Polygon NFTs on OpenSea.

TL;DR - Watch the video at the end of this article!

Today I’m going to show how to mint your NFT (and even buy NFTs) on OpenSea paying 0 gas fees! That’s right! You can mint your NFT for free and the buyer also doesn’t have to pay for gas fees!

OpenSea.io

So, the 1st step to create our NFT is to go to opensea.io and connect our wallet. OpenSea actually supports a large number of wallets, so you have many options.

If you haven’t set up your profile yet, I suggest you do that first. You can insert your name, a short description, a profile picture and a banner. If that is set up already, let’s just click on “My collections”.

Creating a collection

Opensea allows you to create your own collections for free and add items to them! Here you can see the collections I’ve already created, but let’s create another one from scratch by clicking on “Create a collection”.

We have to upload a logo image and can also upload a featured image. The featured image will be used for featuring your collection on the homepage, category pages, or other promotional areas of OpenSea. This is in addition to a banner image.

The name that we choose for our collection has to be exclusive, meaning that we have to pick a name that hasn't been picked by anyone before.

We can also customize the URL of our collection.

Here we can add a description of our collection.

We can choose the category of the collection.

Now here you can insert a website link and other social media links. I recommend you fill in as many of these fields as you can. It’s important to show you have a good presence on the internet, and it allows people to do more research on you and your work.

Now we have to choose the percentage fee that is gonna return to us (the creators), every time the piece is sold on the secondary market, aka the royalties. The maximum amount you can choose on OpenSea is 10%, and this number seems to be pretty standard in NFT marketplaces in general.

We also have to provide our wallet address, which is basically our public key. On Metamask, you can find it on the top. Just copy and paste the number in the "Your payout wallet address" field. Since I have an ENS name, I’ll put that instead.

Moving on, we have to choose between Ethereum and Polygon to be the default blockchain of our collection.

Blockchain

Now let’s understand a little bit better the difference between these 2 blockchains so we can choose the best option for us.

Polygons is an ecosystem of scaling solutions that is compatible with the Ethereum blockchain. I’m not gonna get into too many details in this video, but, by choosing Polygon, you can mint and allow collectors to buy your NFTs without paying for any gas fees!

On Ethereum, we are required to pay gas fees on every transaction we make, but on OpenSea, minting NFTs on Ethereum also doesn’t require any up-front gas cost. This is possible because they use a process called lazy minting, where your NFT isn’t transferred on-chain (or gets inserted in the blockchain) until the first purchase or transfer is made.

Bear in mind that, if the item is being sold for a fixed price, the buyer will pay the gas fee when he/she purchases it, but if the item is part of an auction, the seller pays the gas fee to accept the bid.

Ok, so now that we know how each of them work, which one should we choose? Well, there’s one more factor to consider: while on Ethereum we have the option to auction off our item, at this time, this is not possible on Polygon. So if this is an important feature for you, make sure to choose the right blockchain. I’m gonna choose Polygon for this collection, since my other 2 already have Ethereum as the default blockchain.

Moving on, here we can add payment tokens. Notice that, if you choose the Ethereum blockchain, you’ll have way more options to add here.

We can also choose a different display theme and inform if our collection contains explicit & sensitive content. Click on “create”. And our collection is done!

Add Item

Now let’s add our first item.

As you can see, the maximum size of the file we can upload is 40MB. If your file is larger than that, you will have to compress it, but as we are gonna see later on, you can still include the high resolution version of your file in another field. Since I chose an MP3, I also have to add a preview image.

We have to insert the name of our NFT. It’s also possible to insert an external link to your own website or to a page where people could learn more about your work.

Insert the description for this NFT in this field.

Here you can see the collection where this item is gonna be added. You can even change it if you want.

You can also add properties, levels and stats. These fields are useful if you are creating a collection of characters, or collectible cards, and you want to include different attributes to them.

In the "Unlock once purchased" field, we can add a link to a high resolution version of our file. This link will only be unlocked once the item is purchased. I already explained how to make the most out of this field in an earlier article, where I showed you how to mint an NFT on Rarible. Make sure to check that and learn everything you need to know about using the IPFS and securing the longevity of your work.

Moving on, here, we can insert how many copies of this specific piece we want to make available. By default, if your blockchain is set as Ethereum, you won’t be able to modify this field, but this can be easily changed if we add this code right here (?enable_supply=true) to the end of the URL.

This step is not necessary if the chosen blockchain is Polygon.

As you can see, even though the default blockchain we chose was Polygon, we can still change it for specific items.

We’ll come back to this “Freeze metadata” field, but now, let’s click on “create”.

Freeze metadata

Now that the item is created, press “Edit”.

Here, we can now choose to freeze the metadata, but what does that even mean?

First of all, the metadata provides descriptive information for a specific token ID. Here you can see an example.

By Freezing your metadata, you will permanently lock and allow OpenSea to store it on decentralized file storage. ​​This means, your item will be safely stored and will never be lost or missing. To understand this better, I recommend you check the article I made on Rarible.

Now, it’s very important that you have the Matic network chosen on your wallet. To do that, just click on the dropdown button right on the top of your wallet and sellect Matic. If that option is not showing for you, this means you have to set it up. I’ll also include a link in the description which explains how to do that. It’s really really simple!

Just sign the message and the freezing process will start. It usually takes a few minutes, but it eventually goes through. When the metadata is frozen, we’ll see this message.

Sell

Now we have to put our item on sale. So let’s press “Sell”.

We can now set our selling price, currency, and view the fees associated with our sale. It’s also possible to schedule our sale in advance! Click on “complete listing”.

Since this is my first time minting an NFT on Polygon, I need to do this initial setup. So I have to unlock the currency, which is WETH (or Wrapped ETH), sign the request and sign the message.

Now our NFT is listed!