i have a buncha tools i inherited that u can borrow including big scary power saws lol.
anyway i think u have to weigh the pro's and con's for building materials, for example:
melamine/wood products - pro = lower costs - con = heavier materials
pvc/plastics - pro = lighter weight - con = more expensive
i built my first rack. it was fun to do, it works but the craftsmanship wasn't very precise lol. so i weight the pro's and con's and decided i would buy pro-made/CNC cut enclosures in the future. it was my first rack and i was nervous about escape so it was a lid on tub kinda rack. solid wood was solid, weight is fine:
also to help w/ moving the bulk and weight, u can add handles or caster wheels: https://www.homedepot.com/s/caster?NCNI-5
good luck, post pix!
Edit: also what age Russian Rat are u planning this for? IMO a bb Russian Rat is too small for a 6ft cage. i would be worried trying to find the lil worm in the enclosure just to feed.