Newbie querying heat risers

I want to try making a cast heat riser in 3 sections using kaolin clay & perlite as I have both on hand. I plan on using 1 part clay to 4 parts perlite. Is it necessary to put any reinforcing ( E.g. wire netting) in the clay/perlite mix to prevent cracking?

Hello Lester and welcome!

No reinforcement will be necessary however, you may want to experiment with the amounts of clay. You want just enough to hold the perlite together when packed. Too much will reduce the insulation value.
Because it will be somewhat delicate even when dry, the outer form should probably stay on so its easier to move it around without damaging it. Good luck!