Much like most things on Roblox, you will be making this yourself from scratch, so you'll need to design a t-shirt in an image and then upload it to Roblox.

How to Make T-Shirts in ROBLOX T-Shirts are the easiest clothing to make in ROBLOX. Create an image that’s ideally 512x512 pixels and then upload it to ROBLOX via the Asset Manager in ROBLOX Studio.

How to upload a shirt design to the Roblox Store? To upload a shirt design to the Roblox Store, you will need to have a Roblox account and be a member of the Builder's Club.

Roblox allows players to freely personalize clothing items, allowing them to express themselves and stand out from others.