bottle wall - hole saw for polystyrene

We build a bottle wall (window) in our strawbale house.
We use blue libenfraumilch wine bottles in two dimensions 7.5cm (0,7L) and 10cm (1,5L) in diameter.
The bottles will be mounted in foam blocks, and then plastered.
I designed a hole saw to cut the holes in styrofoam for the bottles.
As an axis I used the m8 screw. I printed the drilling rig from PETG
Styrofoam should be drilled taking frequent breaks. otherwise the hole saw may melt.
Our wall will consist of two layers of foamed pol