can I make a small coal burning stove from mild steel?

[Red'n'Black]

To answer the question, yes you can. Steel stoves don't warp or crack and if you ever rust one through you can chop a piece out and weld in a new piece, for a few quid rather than over a hundred for the part for the cast stove. I use 5mm plate, laser cut and forge up the catches etc over the anvil but you don't have to if you just want something functional.
If you're burning solid fuel, as said, you need a grate with an air intake underneath it. You should also have a baffle plate so the smoke/heat can't go straight up the chimney.
Thanks for the nice things people mentioned about my stoves! Here's a recent woodburner with racks for cooking over the fire...
View attachment 534082

For some reason that one reminds me of the cooking stove in "A Grand Day Out"

 

[julianthegypsy]

For some reason that one reminds me of the cooking stove in "A Grand Day Out"

I can't recall that offhand, but I'll take it as a compliment!

 

[Popcorn]

Very similar