I wasn't able to check out your images (they are private on flickr for some reason, even when I signed into my flickr account). But anyway, of the materials you listed for formwork, pink foam seems like it would work the best. There are plenty of release agents on the market used with plaster casting and the like, and should work fine for your purposes. I've made plenty of rockite formwork out of wood (with paste wax as a release agent) and have had great results. Also, you might want to considering the relative strength of rockite in a model like this, and use some sort of reinforcement (coat hangers, wire mesh, etc). There are some other great threads about bulking up rockite slabs...good luck.

The formwork would depend on the surface texture you want. I have done some nice pieces out of rockite* using plexiglass as a formwork which leaves a nice polished finish to the final product.

And, yes, reinforce slabs if necessary - I would use a wire mesh and possibly try to get the ends to be exposed (possibly lightly sand the edge of the rockite and reinforcing so that the wire is flush with the surface). This would point toward the techtonics of how it would be built.


* I am assuming that you are talking about a product "Rockite" which is basically cement with no aggregate mixed with plaster.

form work in acrylic or formica if everything is flat.... add some sand to give it some holding power... reinforce with wire mesh/drywall mesh...make sure to vibrate the formwork to release air and maybe have air holes to release any undercuts/etc....

I'm not sure why you can't see the images invisiblecanook, I checked and the permissions are Public.
Maybe try this? http://www.flickr.com/photos/jbrewlet/4147866260/
http://www.flickr.com/photos/jbrewlet/4147107239/in/photostream/

I'd love to use something like acrylic or formica but it's not flat. Otherwise I'd not have to CNC it. Its not super complicated but its a tapered floor plate of which 1/3 is a cantilever.

I've thought of reinforcement but it sounds incredibly difficult. How would you float it in the center in such a small project tyvek and zug?

thanks for the advice so far.

have the floor plate cnc'd from mdf or make it from acrylic.... make a 2-part mold from that part and then you can cast your parts....

depending on the size/etc, i would just make it out of acrylic and use bondo to make the tapered surfaces..... since you can laser cut 2 layers of 1/8" and use the bondo to slope where you need to....make sure it's flat when you start though.

modelbuilding101.com

my site... my last forum template had a meltdown so had to start over....