Casio AP500 Keys Hammer Cap

Something I had some problem with. My daughter old Casio Celviano AP500 electric piano having its keys sagged. Upon inspection I found these rubber pieces decayed and fallen to pieces...

I've checked the internet for spares, it cost USD3 a piece... with 88 keys in total, that'll be quite expensive...

Anyway the original material is rubbery type, therefore the caps that I printed using TPU i.e. flexible filament. The attached STL files contained complete number of caps for the whole 88 keys.