From thumbnail sketch -

To an 8"x8" collage of pieces of iron-on interfacing. The silk I planned to use was too floppy, and by using the interfacing for the finished shapes, the edges could be ironed under -

If you're using this method, remember to cut the templates with the iron-on side face up - otherwise you'll end up with your picture reversed.
OK, here all the pieces have their raw edges ironed under - and to get the pointy bits to behave, I lashed the seams across the template underneath - no stitching showing (in this silk, extra stitching might leave holes). The handle on the left is printed velvet and on the right, some polyester damask -

The next photos show the kettles sewn down and padded, ready to quilt. I suspect the vast expanse of copper kettle might need a scattering of interesting stitches (after all, the original is battered and scratched, and there's even a hole near the top - we use it on the narrowboat).
My first idea was to mount this piece on a ready-stretched deep canvas, but maybe a border is a better idea. So, which one??
A:

B:

C:

D:

- or something else? This is the decision point at which things start to morph into UFOs...