So, I've been experimenting with expanding polyurethane foam to injection mold a HAB capsule.
My first experiment was to work with a big block of foam that I sprayed onto a sheet of baking parchment. The foam doesn't stick to the parchment and it can be easily peeled off. The set foam can be easily cut with both a saw (a bit messy since small parts break off) or with a Stanley knife. The Stanley knife gave clean cuts. It was also possible to hollow out a space inside the foam where the electronics could be stored.
One test I did was to see how strong the cured foam is by hitting it with a hammer. Here you can see the hollowed out capsule as I hit it with a geological hammer. It seemed strong enough to me for a HAB landing.
I then tested various glues and paints on the surface. Here I've painted it with spray paint (yellow) that is solvent based, again with the acrylic paint I used for the GAGA-1 capsule, then drawn on it with permanent markers, stuck on some yellow duct tape, glued on with spray adhesive some space blanket and used epoxy to stick some more space blanket in place.
The duct tape stuck well, but I wouldn't use it as the only means of keeping the capsule sealed. Next I left the capsule in the freezer (at -18C) overnight to see if the foam became brittle.
Next I moved onto the injection molding experiment. I made a mold from a thin sheet of cardboard that came from a dry cleaner (used to hold folded shirts) coated with baking parchment. This was rolled up and taped and a piece of parchment used to seal one end.
So, I think I could put together a HAB project whose goal would be to go for maximum altitude with a total capsule weight in the 100s of grams (including a very lightweight video camera this time).
Will have to see if I have time to work on GAGA-2: Baby Gaga.