Had a bit of a rethink after this, settling on name spacing more like this at the moment. Quite enjoying the cycle of build/try/improve.

const in1 = draw.rectangle(size1, size1).fillet(2)

const in2 = draw.origin([0,0,height1]).rectangle(size2, size2).fillet(2)

const result = make.loft([in1, in2])