Hi folks,
First post here, so my apologies if I’m in the wrong section. I am building a marimba (like a wooden xylophone), and I am modeling the keys in Sketchup. So I am trying to figure out how to do two things:

create a rectangle shape and then copy it and every time it is copied it is a set amount of length (let’s say 5/8") shorter than the copy before. There would be something like 35 keys, so I’m hoping to figure out a way to do this without having to adjust each one individually. I need to figure out how to graduate both length and width.

Have a rectangle with one length (say 39") and then another with a length of 10" and choose a certain number of keys that will fit inbetween them and have sketchup automatically determine the lengths of those. Said another way: The first key is 39" long. The last key is 10" long. I want 35 keys in between those two keys. Can sketchup determine the lengths that they will be?
Thanks for any help!