Publishing a large NFT collection on OpenSea:Part 1
Published: 2022-04-08 08:31:20

You have been following the exponential growth of NFT transactions. You keep hearing about 12-year-olds who have made millions selling NFT’s. Perhaps you have even bought a few NFTs or even created a small collection yourself. You know that large NFT collections are where all the action is. I’m writing this in early April 2022. This is what the top collections chart by transaction volume looks like:


![](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/ee570sz86hc3mnaikrcb.png)

You need thousands of items to become a top-tier collection. How does one create such a large collection? It’s very different from building a small collection manually. In this article, we will describe how we published the Krypto Pandaz collection.
We will focus on the technical steps. We are not going to cover marketing, the initial sales process, and other activities that you need to get right to have a relevant NFT collection.

The technical process involves multiple steps. We have divided the content into 3 parts:

- Part 1 (this story)
Decide which blockchain you want to use
Define a smart contract

- Part 2
Create images and a metadata server

- Part 3
Setup Infura
Add crypto to the wallet you will use to deploy the contract
Deploy the contract
Mint tokens
Setup your collection on OpenSea

## Prerequisites
What skills do you need to have or hire? :

- Understanding of how blockchains work
- Solidity — smart contract definition language
- A modern development language that can manipulate images and has libraries for web 3 — we will use TypeScript
- Art skills to create image layers
- Armed with these skills, we can start the process of generating a large NFT collection.

## Decide which blockchain you want to use
OpenSea currently supports the following blockchains:

- Ethereum —the largest of all 3 in terms of NFT items published on 
OpenSea. It’s also the biggest in terms of spending. People spend 100x more on NFT’s on Ethereum than on NFT’s on Polygon. Ethereum’s problem is high gas fees. When you publish a contract, mint an NFT, or approve a transaction, it costs money. Especially minting NFT’s is expensive if you have thousands of tokens to create. At the time of writing, the costs of minting 10k tokens through a standard ERC-721 contract on Ethereum go in thousands of dollars.

- Polygon — Ethereum’s L2 network. It has much lower gas fees. It 
will cost you less than $100 to publish an ERC-721 contract and mint 10k NFT’s. The issue here is that people are spending 100x less on NFT’s on Polygon than on Ethereum.

## Klatyn — recently added by OpenSea. It’s compatible with Ethereum 
smart contracts. It has the smallest footprint on OpenSea. I’ve not explored it much.
For our first collection, we decided to go with Polygon. We were not comfortable with the upfront cost that Ethereum required. We wanted to learn the process and be OK with making mistakes with smaller amounts of money.

## Define a smart contract
It’s time to define a Solidity contract. OpenSea supports so-called ERC 721 and ERC 1155 contracts:

- ERC 721 — this standard describes how to store information about 
NFT ownership on Ethereum. It also defines what operations can be performed and how they happen. In most basic terms, an NFT is a place in a smart contract that can hold ownership information. There is no NFT metadata in the contract. When you buy an NFT, you instruct OpenSea to insert your wallet address in a map in the contract that manages the NFT.

- ERC 1155 — this is an extension to ERC 721 and currency token 
contracts. It defines how to store many tokens and many NFT collections in a single contract. If you intend to deploy multiple NFT collections or want to mix an NFT collection with a token, ERC 1155 is the way to go.

[Go to Part2](https://dev.to/topsoftwareengineer/publishing-a-large-nft-collection-on-openseapart-2-3e3m)