Seeing as how I am an "expert" with a hand held grinder - Thats how ...

Size ... 3mm steel plate - I'll ask the metal shop guys they'll know if that's too thin or not ..
The hotplate might have to be stainless but would be harder to work with ??
The ash catcher would be 1 mm steel and big enough so all the bits lay flat in it for storage ..
That hole - is for the billy -- Not real sure why I did that

xcavator has made one - I just grabbed his idea and reworked it a bit .. There's a thread here someplace
on his build ...
Cheers
M