http://www.mybdsm.com/pages/device/cd1.html FOR > 18 YEARS of course
explore the site, its full of explanations and pics like
http://www.mybdsm.com/pages/device/cdrev1.html
If you are able to work plastic sheets you can do this one. Try with cardboard first.
I think it can be done also with this plastic used to do small repair and that melt in boiling water.