Hypertufa containers

I am thinking about making some hypertufa containers this winter to plant up with alpines. Covered an old sink years ago but I want to make these from scratch
Wondering if anyone has any tips - first of all the recipe, to include perlite or vermiculite or not? Also does coir work as well as the peat traditionally used.
Then size - is there a minimum thickness for structural stability? wire netting re-inforcement required?

Would be nice to hear from someone who's done it

 

I have done it once or twice. I used those black boxes which Garden centres use for plants as a base, but have also go some polystyrene fish boxes covered in it too. Never managed it using wire covered carboard boxes though, they tend to go mis-shaped for me.
Mix I used was standard one part sifted composted bark, one part sand, one part cement (I think, will have to check up on that to be sure). Never added either perlite or Vermiculite nor chopped fibre glass as in some American recipes. Anything with a fibrous nature would do, so yes Coir would be ok.
Will try and find the link to the Article I wrote for the Alpine Garden Society magazine.
Only other thing is WEAR GLOVES! Cement is a strong alkaline and can burn the skin off your fingers. I found out the hard way when dealing with the DRIED hypertufa and only did not suffer very badly because I realised what had happened and washed my hands in vinegar to neutralise the alkaline.