||I use a wide variety of plastic "stands", risers, supports, etc. I use LOTS of liquid thumb-tack type materials, a little tape, and various small things to "lean against".
I buy scrap plastic on E-bay (where else?)
Look for scrap at Glass & Window Shops too, they usually have some and they often sell it by the pound.
You do not need large pieces. It serves well to keep some of as clean and scratch free as possible. Clear and black are very good, and can be used to produce nice reflections.
The black acts almost like a mirror with even reasonable lighting.