|This tip uses materials that should be easy to find:
1) Plastic canvas
3) Magna-Tac 809 (a clear adhesive used in making bridal headpieces. Comes in a nozzle bottle)
Cut two pieces of Timtex and one piece of plastic canvas in the size of your bag bottom. Use Magna-Tac to glue them together as such: Timtex, plastic canvas, Timtex.
The result is a layered and padded shape that is sturdy but not too stiff. If your bag bottom is more than 3 inches wide, and/or if you need something stiffer, you can also substitute plastic cut from a disposable plastic food storage container.
If the plastic canvas or food storage plastic is not big enough just butt pieces together and then cover the join with a smaller piece of the same material.
A small piece of food storage plastic is also useful as a backing for both sides of a magnetic snap – you won’t feel the prongs as you open and close your bag.