A far off dream but

I’m an amateur banjo player, but have been playing bass guitar for 20+ years. I’ve seen some DIY “bass banjos” and have been interested in attempting to build my own. I want to try and make a standard banjo, not a stand up. Preferably a 5 string, not sure how I’ll figure out tuning but that’s a problem for future me. The real question/request is any info on how to move forward in my attempt