Loved watching Final Space, and particularly loved Avocato’s helmet!
Where to buy online
TeePublic (US and UK)
Threadless (US)
CloudCity7 (UK)
Amazon (UK)
NeatoShop (US)
PopupTee (US)
Society6 (US)
You can find the design on t-shirts in most stores, but also on other products depending on the store (e.g. hoodies, mugs, stickers, notebooks, phone cases, greeting cards, cushions, socks etc).