Here's an interesting hobby side note-Schmidt was the printer of the 1909-11 Obak baseball cards, which are some of the most beautiful cards ever made, and certainly printed a host of other sets before and between World Wars 1 and 2. Stecher-Traung was known more for their fruit crate labels, which were also works of art.
The Osborne Register Company did some "minting" for Topps from about 1948-52, especially the earliest versions of the Golden Coin issue.
Topps had a Japanese manufacturer for certain novelty items in the 1960's and early 70's but some U.S. Customs issues may have curtailed that relationship. That is definitely a work in progress on my end, However, I have seen many references to a Canadian Manufacturer Topps used to make its 1964 and 1971 Baseball Coins, a firm called Space Magic Ltd. of Don Mills, Toronto, Ontario. This would be fairly close to where O-Pee-Chee was headquartered in London and it would make sense that Topp's Canadian partner would have been able to source a manufacturer for them.
Pretty much any baseball collectors knows about these colorful coins, which are printed on light aluminum, have rolled edges and came inserted in packs of Baseball. Here's the 64's:
The 1964 coins were printed on large 255 coin sheets, as this Leland's auction from February 7, 1992 shows:
You will note there is no reference to Space Magic, so it's a bit of a leap of faith that they were manufactured by them, However, I think it's correct once you look at this next item. For instance, this largely uncatalogued set of 20 Batman coins from 1966 bears the Space Magic Ltd. name:
There was no second series incidentally. That blueish color looks like a dead match to me. The coins are pretty pedestrian and used the very mundane comics artwork of the time to cash in on the TV series but the shields used to house the coins are spectacular:
Holy crap Batman!
The 1971 Baseball Coins were probably issued in three groups, each having 51 coins. 51 is interesting because it divides evenly into 255, so five complete series could be run on a full sheet. Here is one of the 51 coin series sheets in proof form
There are a number of other aluminum coin sets out there, most from the 1960's. The 1962-63 Salada Football Coins, the 1963 version of Salada's Baseball Coins, 1962-63 Shirriff Hockey Coins (Shirriff was owned by Salada), 1965 Old London Baseball Coins, and probably a few others I am missing. I suspect Space Magic Ltd. made them all, even though not every one divides neatly into a 255 coin production sheet.