instructions.......i didnt find any - i just made it up 
I use cable ties to hold the 90 deg shape as well as proping it against stuff while i work - once its all set its rock hard so it doesnt matter (but must be in the right shape before you start!)
Its very light relative to its size because 20-30% of the structure is foam......in water its even lighter as the foam floats....the bit i did still sinks easy enough though!
the foam is tacky before it cures but not tacky enough to stick sand a little lumps of rock on.....within seconds it forms a dried skin long before it goes hard....hence the epoxy.
i'll post pics as i go....the next bits will have lots more caves and tunnles.
I use cable ties to hold the 90 deg shape as well as proping it against stuff while i work - once its all set its rock hard so it doesnt matter (but must be in the right shape before you start!)
Its very light relative to its size because 20-30% of the structure is foam......in water its even lighter as the foam floats....the bit i did still sinks easy enough though!
the foam is tacky before it cures but not tacky enough to stick sand a little lumps of rock on.....within seconds it forms a dried skin long before it goes hard....hence the epoxy.
i'll post pics as i go....the next bits will have lots more caves and tunnles.
