How to make shirts and trousers on Roblox. You'll be best off having a couple of templates for this! So take a look at the the image below, and you should gain an idea of what your T-shirt design ...

Roblox is a large-scale multiplayer online game platform that allows users to make and play games developed by others. It debuted in 2006 and has since grown to over 150 million monthly active users.

On the Roblox website, there are several templates. One can use those PNG files, which have a transparent background, as inspiration while creating the design for the shirt.