Oooohhhh, good one!

Timtex

I bought some fusible batting from JoAnn's that is very heavy and makes a great bottom for purses when sandwiched between 2 pieces of material.

That's what I do. Often you can fnd some even at close-out prices...odd ones that didn't sell with the groups.

Go to an xray place and ask if they will give you the plastic that the xray plates come packed in. It's very stiff and they usually throw it out. You will need very sharp scissors to cut it.
I'm in Australia so not sure if it's the same in other countries.

I used cake decorating boards. :-o

The form board works best for me and so light weight, Marcie

I rip the plastic covers off of 3-ring binders and use the cardboard that is on the inside. I will be loading up on used binders in a few weeks because I teach high school and kids will soon be doing their end-of-year locker cleanout! It's absolutely amazing what they throw away!

My hubby has made them for me out of left over paneling. They work great.

I used a double layer of plastic canvas in my mini bow tuck. Works great and is also very inexpensive.