Not an alarm, but a timer app.
https://play.google.com/store/apps/details?id=com.persapps.multitimer
MultiTimer is brilliant for having a dashboard of purpose made timers that I use all the time (weekly baking, laundry, tea timer, etc) and ad hoc timers.
Good for you! Seriously!
For the rest of us, a few notes on how you accomplished this would be sha-weet! I think sketch up is the most approachable 3d program, but all my “post Windows” attempts have resulted in crashes and freezes. 😥