So, back to the drawing board and change from 3v dome to 2v dome - it means less triangles for the same circumference.
Also, I have decided to make plaster mould rather than wooden one as it is more rigid.
With this size and shape mould, I will use paper plaster. It has many benefits - I don't need to use cottles, it uses significantly less plaster, which makes it lighter and it is very strong.
Here we go:
left: cardboard model, protected with sticky back plastic
middle & right: applying the "milk coat". Sometimes I make slipcasting moulds the same way so I am in the habit of applying thick "milk coat"
left: smoothing first layer of plaster
middle: finished first layer ("milk coat")
right: mixing second batch of plaster and adding paper pulp ( as soon as plaster has absorbed water)
left: paper plaster can be applied immediately - addition of paper makes it stiffer sooner so it holds it's shape