This looks to be a windshield for a canister-top gas stove, where the cookie tin lid sits somewhere between the burner and the canister. Is that right?
In which case, why not simply make a cylinder of flashing, and support it on a three-legged wire (or folded flashing) support held in place somewhere between burner and canister? I don't see that the solid lid provides any useful function other than supporting the wall of the windshield.
The advantage of an open base to the windshield is that you don't restrict the air supply to the burner, allowing you to make a fully cylindrical windshield, which you can lock together with simple slot-and tab fastenings (upper one with tab on outside, lower one with tab on indside). This joint allows you to roll the windshield up for storage inside the pot. If you make the slot/tab joints in the right place, and the right size, they can allow clearance for access to the valve.