"This seems like an addition to the "pointless use of concrete" category that's so popular recently. Concrete is an incredibly polluting material due to the massive amounts of carbon resulting from the cement production process. Using it for anything that you don't expect to last decades or centuries, after which time it may have offset it's carbon footprint, is reckless. I'm all for material experimentation but only to the end of finding new or novel uses for which the material is suitable. Even most eco concrete simply offsets it's carbon footprint a tad quicker.I make plaster and concrete moulds regularly as part of my job, this looks like the aggregate mix was wrong, the mold wasn't vibrated enough and co-efficient for expansion/contraction of whatever mix used was simply ignored causing clear deformations and loose material intersections. The kickstarter also mentions the patina the "natural" concrete develops, which leads me to believe the concrete is not sealed. This simply could not be food safe. If any contaminates caused mould to develop on the surface of this machine it would be nigh-on impossible to effectively wash. If this complies with CE certification I'd be shocked (and so would you potentially if the device were to get wet)."

"Like to just point out this was just for roughing out the body routs."

"I've used paper templates as a mask before to mark out guitar bodies. laid down the paper with low-tac spraymount and spread pencil lead filings from a parer out over the edges of the paper. This was done in a pinch but you could do this with just about anything indelible as long as the mask doesn't absorb it. Even cut out the pickup and bridge routs from the mask and worked inwards for those. "