3D printer design experts

lisaviolet thought this was worth mentioning said

My husband wants me to make a box. I haven’t a clue how to do this. I’ve just done stuff from thingiverse so far.

It’s taller on one side (the short sides) than the other.

bottom dimensions (in inches) - 3.75 x 8.25

Tall side: 6 inches

Short side: 2.5 inches

He’ll be putting pieces of steel in it.

I’m looking at thingiverse for something I can modify. I’ve learned from you guys it’s not that hard to do.

But how would this be built from scratch? Any good tutorials on this?

Thanks in advance.