Good heavens, I’ve spent the last four hours watching Youtube videos! There are a million methods and schemes for building or buying raised beds. Last year I built my own using purchased boards and hinged plastic corners designed specifically for raised beds. Those corners were shot after a year and a half, just cracking and falling apart. So this year I bought two smaller — 4’ x 6’ I think — galvanized steel beds. They cost less than those dang plastic hinges! As always, however, the problem with raised beds is getting them filled. Our desert soil is largely useless for growing veggies and such, so decent soil, compost, amendments, etc., have to used. Hopefully all of this can be reused for several years, with minimal annual additions. We’ll see . . .
You don’t have to use all soil. You can put logs and twigs and all kinds of trimmings and whatnot in the bottom if you have stuff like that around and do maybe 12-16” of solid soil.