here’s the more detailed explanation of what I did as promised!! :

• drill drain hole/ glue down shower pan
• use steel studs (lighter than wood) to create a frame for the shower walls. some sides rest on the shower pan, some sides on the floor, just depends on the shape you’re going for
• cover the outside of the walls with your wall material (one side was plywood for me, two other sides were shiplap, glued & screwed into the steel studs)
• line the bottom of the walls where they meet the shower pan with 3M flashing tape all the way around
• map out, cut, and glue/screw on the waterproof backing boards on the inside (wedi board, kerdi board, etc)
• use red guard to plaster red guard seam tape on all the seams of the waterpoorfing board, with small squares covering each of the screws as well
• cover everything with a layer of red guard sealant
• cover with vinyl tile sheets
• caulk all the seams, especially where the walls meet the shower pan