1. Log into the account and click "Create"
2. Hit the button "Dashboard"
3. Select "AVATAR ITEMS" → "Classic T-Shirts", then press "UPLOAD ASSET"
4. Select the corresponding material and hit "UPLOAD"
5. Return to the "AVATAR ITEMS" page and click on the created T-Shirts
6. Modify the status to "On Sale "→ Set the corresponding price (note that the roblox official will charge a 30% handling fee) → Click "PUBLISH"
7. Click on "PUT ON SALE" (the official will charge you 10 ROBUX for publishing products)
The production and listing of tradable items are completed. (Note: Trading and creating items require you to have a membership)
8. Return to the "AVATAR ITEMS" page, click on the three points at the upper right corner of the created item to copy "URL", and send the link to the seller. The seller can purchase the item you have listed through this link