Help! I need 3D Printing related gift ideas.

I'm sure many have this problem of, what do I buy for the person who has everything I can already afford? 'cause I have that problem now. My dad has gone deep into 3DPrinting in his retirement (he handed me down my Ender 3). He's got both an Ender 3 and a resin printer, tho I can't remember what model.

I was hoping to pick the hive mind for some useful 3D printing related ideas that won't break the bank. Some useful utilities that maybe I hadn't thought of. I'd really appreciate any help.