Expanding (foam)

MDF blocks aren't so bad, although making one is timeconsuming and annoynig (trying to find the right size drill in the workshop takes ages. oh wait, anything in the workshop takes ages). Also the blocks are heavy, which makes them unstable. So I need to find better material for my modules. First try - expanding foam. It's expensive (~6£), so I'd better use it. 

First of all I had to make a mould, so basicly reverse the shape I made the other day. It looked like this:

Since the foam is used also as an adhesive there's a risk that it will stick to my mould forever. It's not really what I'm looking for, so I had to use something what is professionally called "releasing agent" - known as vaseline. Again expensive (1£ for 20g) and I have used nearly half of the box while coating my mould with it. Then I had to sprinkle some water inside which makes the foam work.

Now (after reading the instruction carefully*) I sprayed some foam inside:

Way too much. The foam expands 2.5 times, but mine expanded like 4 times and now looks like this:

Such a waste of foam. Could have 2 blocks instead of one.

I'm still not sure if it will work. The foam seems to be dry, but might be wet inside, so it's better not to touch it. Apparently it's safe to sand after 12h, so I'll just wait. Also I need to get rid of excessive foam, cut it neatly and disassemble the mould (not easy - glue gun seems to work extremely well on moulds, so you can't take them apart unless you're super strong, but when you want something to actually stay stuck together forever then of course glue gun won't work, nooo way).

So question of giant lego foam block remains unanswered.

* I skipped the boring stuff.

PS. While watching foam tutorials on you tube I've stumbled upon video of amazing cos-play artist (?). The woman from Germany makes really impressive costumes and props inspired by e.g. World of Warcraft. This is her website http://www.kamuicosplay.com/