Sam, thanks for the patent numbers. Besides US 2,766,606, I managed to find the Spanish patent and others on the European patent web site (a translated abstract is at https://worldwide.espacenet.com/publ...05970A1&KC=A1# and the patent itself, in Spanish, at https://worldwide.espacenet.com/publ...&locale=en_EP#). The Spanish patent seems to be matched by ones in French (https://worldwide.espacenet.com/publ...1064536A&KC=A#) and German (https://worldwide.espacenet.com/publ...1004065B&KC=B#).

Another patent that looks like the Manifoil is Great Britain 761,432 (https://worldwide.espacenet.com/publ...&locale=en_EP#).

Finally (for now?) a later Canadian patent 549260 also looks like the Manifoil (https://worldwide.espacenet.com/publ...=549260A&KC=A#).

Some or all of these may not be for the Manifoil itself but the drawings resemble it.