What can I use in place of acrylic for my mock-up/prototypes?

I'm working on a custom-made pencil case and I intend to do the final version with a lasercut acrylic-sheet that's been shaped around a positive wooden shape. I'm still working on the details of how I want to place the cuts and lines, and would love to be able to make some quick prototypes that I can draw on and carve out (maybe something paper-based?), but I'm short on ideas of how to do this and what materials and techniques to use. I've added an image of the positive shape and some sketches (sorry for the crappy quality).The shape can be split in the middle to allow it to be pulled out at the ends after the acrylic sheet has been shaped around it,

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In my mechanical drawing class and engineering drawing class, we use pressed cardboard for prototypes, since it's not corrugated it is very strong. It is about the same density as MDF

Flark (author)  sean_sylvester13 years ago
That's a great suggestion. In my experience, using warm water to make the cardboard soft and shapeable, and then leave it to dry is a super fast and cheap way to test these kind of shapes.
klee27x4 years ago
First thing I would think of is closed cell PVC foam board. This is different from regular foam board. Try googling "PVC foam board," or "Sintra." It bends at a much lower heat than acrylic. Can be bent with a heat gun.

I dunno how thick the acrylic you plan to use, but you can also try sheets of ABS or styrene. Again, much lower melting temp than acrylic.
Eriswerks7 years ago
You might try using sheet PVC plastic. 3mm is a common thickness, and it is somewhat flexible in small pieces, heat bendable, and easily cut with a utility knife and ruler. If you use a heatgun on it and then throw it onto your form, I think you'll find that it bends to your will, so to speak. 6mm and 10mm are also pretty easy to find.

I work in a sign shop, where this is a common material. You can ask them for any scrap or damaged pieces, or simply look in their dumpster... fairly big chunks get thrown away all the time.
uguy8 years ago
Craft stores such as Hobby Lobby and Micheal's have a craft foam sheets which is very flexible and easily cut with scissors or craft knife. It comes in colors and I think it might work for your prototypes. Seems to me it's about 1/8 to 1/4 inch thick.
Flark (author) 8 years ago
Acrylic and a hot air gun is exactly what I'm planning on doing the final version in. I've even done a couple of tests, and they work fine. Only problem is they take forever to make, and it's really time-consuming and difficult to subsequently cut the acrylic shell to see what cuts and curves work together. Your thought about vacuum-forming plastic might work. As I remember, it's usually a good deal thinner than acrylic, and should be faster and easier to bend and cut. Your other suggestion about transparencies is one that I have considered, but not sure if it'll be too weak. It might work great for the case of a simple prototype and shape-study though, and the double-curved design could actually help make it sufficiently rigid. Either way, it wont hurt to try :) Thank you a lot for the suggestions :) They are greatly appreciated.
Flark (author) 8 years ago
Thank you for the suggestion. I do have both foam and a hotwire knife available, but the surface is double-curved and I'm not sure that the foam will bend the way I want it. Maybe if I carved it into alot of thin pieces, but then it seems to become too much effort. what I was hoping to find was a cheap material in form of a sheet, maybe simply standard A4-sized, that can be easily bent or shaped over a form and then somehow hardened afterwards.
Working on an instructable for that "CNC working wax" Steve