I built mine this week. I used 1x3 boards cut at 45 degree angles, used gorilla glue on the corners and a corner brace on the inside and outside. I made four 4'x3' panels. I am stapling the spandex to apply but slightly worried about it ripping. So I was wondering how dragon does it.
I saw a video on youtube where a dude cuts out an inlay and has a board that snaps in to hold the fabric, so it can actually be changed. I didnt have the tools for that.
Finishing up tonight on last of spandex and then it will be done. $150 total for materials. Will post a picture.