Testnet
Scatter supports Sepolia testnet which enables you to experiment with deploying and modifying collections for free.
If you need test sETH use: https://www.infura.io/faucet/sepolia or https://www.google.com/search?q=sepolia+faucet or https://faucetlink.to/sepolia
The testnet is still a public blockchain so anything you publish there will still be visible to others. With that in mind, we recommend you use dummy data, text, and images when deploying your testnet collection. Eventually every testnet is retired but this can take years to happen and it's likely someone somewhere will still archive it.
Another way to test is to deploy on Base chain. Transactions on Base cost a fraction of a cent, so you can easily use it for testing. We recommend you to create a separate address in your wallet for it to prevent your main address being spammed by test NFTs.