In 2019, Roblox changed these memberships. They're now called Roblox Premium, and they work a little differently than the earlier Builders Club (we'll touch upon that in a bit).

Launch ROBLOX on your computer. Click "Builders Club" in the middle of the top menu. Select any of the Turbo Builders Club or Outrageous Builders Club memberships.

Only members of the Roblox Builders Club can make shirts and pants but no membership is required to make a T-shirt.