No casting has been done yet, this is still in the design stage.
Thank you for your excellent constructive criticism regarding the draft angle and mold release, you are absolutely correct.
I had been thinking of using a 3D printer to make a negative of the grid positive mold, to cast numerous grid positive molds out of hard expanded foam, for a larger application of many acres using a very large number of pallets. I think this approach will still work, but the grid positive mold would have to be made of latex rubber rather than expanded foam.
But for a smaller installation it makes more sense to use a router to add some draft angle.
I adapted this old pallet and box design to a very large scale implementation covering many acres, using a roughly 5% epoxy 75% hard expanded foam chop 20% sand mix instead of papercrete, and had planned on using this mix there, the costs versus longevity and structural integrity are much more favorable.
Epoxy:
$2,000.00 per ton is $0.0196773 per cubic inch
Hard expanded foam chop:
$2,000.00 per ton is $0.0000391 per cubic inch
However, I wanted to go back and redo the small 4 place box to give out something to the smaller producer, and update that ancient 4 place design with some of the newer elements to drop the price, like the arched removable walls and wall based manifolds to drop the cost.
Apparently, given your analysis of thinner papercrete castings, the 5% epoxy 75% hard expanded foam chop 20% sand mix would have to used there as well for the pallets instead of papercrete, but I still think that a papercrete box and floor is still the better choice for a small scale build like a 4 or 16 place box.
Therefore, the main info I still need would be the papercrete cost for the estimate and the cheap coating materials info.
5% epoxy 75% expanded foam chop 20% sand
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