Yes "maker" is good, or even "builder". Both are probably more accurate than "manufacturer". "Assembler" is a bit special, and in my mind I keep this for those who opened the crate and literally put the parts together. There was a bit of this in Australia in the early days: I suspect the Sun Villiers in veteran years is a good example. Most Australian makers/builders started with imported lugs and parts, and local "vision", and went from there.
Rims either side of the WW2 years is an interesting topic! It turns out that bicycle and motorcycle rims were on the list of controlled imports and were probably not available from, say, 1940 until January 1946 when they were removed from the list. I recall Malvern Star had to massively retool to keep bicycle production going during the war. Anyway, here are some extracts referring to imports of rims (and engines, hubs, and other unclassified parts) after the ban was lifted. 70 bundles of motorcycle wheel rims!
I wonder if the pause in Acme production between 1941 and 1947 was due to shortage of items like rims.
Leon