Ah,like so,so many things, this used to be totally, 100% free! This is the tinkertubes .PDF file showing dozens of DIY studio lighting devices that can be made from good old PVC pipe, and the various elbows, T-joints, threaded connectors, and good old sweat equity, a tape measure, and a hacksaw...
Photoshop Training and Photography Training Tutorials - Software Cinema - Tinkertubes
When I was a young man, Dean Collins was the Number One Proponent of what came to be known at the Lightform Panel system,which was handled by the Bogen company.
It featured the venerable P-22 panel and the P-42 panel There are a few Dean Collins video segments available on the web to watch for free. Dean Collins did not invent panels, or scrims; they were a natural invention of the early Hollywood movie lighting directors, who used large wooden or metal frames with large expanses of silk or cotton fabric to diffuse,shape,and reflect and modify light back in the very early days of motion picture making in Hollywoood,California. Sometimes, you might encounter the term "silk", in place of scrim, or panel. Scrims, panels, silks, diffusers, diffusing screen, screen--all of these can refer to basically the same thing or something pretty similar. Scrim Jim is a high-end one today, as is California Sun Bounce.
New ones are rounded and collapsible....great for portabillity and great for cheap shipping from
eBay to you, but much harder to gang up (aka join), harder to prop up, harder to stand up, harder to secure with cheap $2.49 A-clamps from Mega-stores, and harder to make your own fabrics, and almost impossible to fit to found fabrics or materials...I know people like the rounded or oval-ish collapsible reflectors, but they are less-efficient at actually reflecting or diffusing light, per-diameter (area = do the math),and in general, you will find that square or rectangular panels make life easiest in almost all ways--except breaking them in to ultra-compact package sizes!!
To me, something in the 42x72 size range is "standard" for full-length people. it is actually big enough to do the job it is needed to do on 1,2 people....on groups of 3,4,6, tyou will want two panels quite often, clipped together. 3x3 or 4x4 is also very handy.
Google for Dean Collins videos, and be prepared to see how flexible this idea really is. There is a guy, I think his site is Lighting Magick (with a k at end) who has a for-sale course, plans, supplies, and free theory/lessons. He used to at least.