what species of bats are you aiming to house ?

Also are you looking at permament colonies or simple shelter for transient bats.
I've done a little study of bats over the years (yes I have a bat detector :-) )
Obviously a lot will be country specific, but overall bat habits should be fairly universal.

The bats that are in decline and need help tend to be the very small species that tend to have a variety of roosts that they move between over the year - even a small bat can roam as far as 30 miles in an evening. Because of habitat loss, over urbanisation, improvements in building insulation and materials and techniques. The traditional roosting places are in decline, also predation - particularly from domestic cats - accounts for a huge decline in bat numbers.
Obviously in the states there are snakes, raccoons, tarantulas etc that will also prey on bats.

These bats do not need huge living spaces and tend to avoid them - for the obvious predation reasons.

It just seems that you're concentrating more on the actual build - with an emphasis on large, inpractical housing for a very small segment of the bat community - rather than the species that really need transient shelter.

The other thing is that your emphasis is purely on 3d printing as much of the house as possible. I find with larger projects that you can usually source the larger parts from something that's cheap and readily available and use 3d printing to fix things together, make joints, brackets etc.

Why print large cylinders when your local hardware store already sells plastic pipes/tubes in a huge variety of materials and diameter and colours - both stronger and cheaper than you can print.
Throw in a hacksaw and a drill - and the 3d printing becomes minimal and more practical.

For a school project - starting with cheap readily available materials, and adding a few easy to print parts to convert it into a bat house - would make a lot more sense. Both from the cost and practicality side of things.

It would also be very easy to scale up or down for different species and usages of bats.