Looking remarkably like an "all-lever-change" Mk. 2 Deckel FP1 (a machine considered to have set the standard for this class of miller) the "German" Macmon M100 was identical in appearance to the Prvomajska ALG100, a machine constructed in Zagreb in the former Yugoslavian Republic. Exactly what the connection between the two brands was it not known  and to confuse matters further, some examples built in the 1960s have been found with "Macmon AG Dübendorf, Switzerland" labels as well - possibly to "hint" at Swiss manufacture by association - the factory clearly denying that the machine was ever put out in part or whole (except for the Yugoslavian version) and that no records exist of Swiss production. Further confusion has also been caused by (according to a machine-tool contact in Europe) the alleged habit of Prvomajska dealers attempting to increase the appeal of their wares by fitting them with Macmon badges. If you can add to the sum of knowledge concerning the origins of these millers the writer would be pleased to hear from you - as indeed one has with the following interesting observations: Dear Tony - first, thank you for your very informative site, where I found lots of knowledge about all kind of machines! I have owned for 30 years a Macmon 100 (Dübendorf). I do believe that Prvomajska made the machine since mine has an Ex-Yugoslavian motor inside (according to the manual) and when I changed its bearing found a tag from a Yugoslavian maker. If the motor had been Swiss the tag would have read BBC - not the British Broadcasting Corporation but that well-known maker of motors in Switzerland, Brown, Boveri & Cie.) Since the former Yugoslavia was from the communist east-block, they managed somehow to pretend to be Swiss to increase sales - though perhaps for sales in Switzerland that had to make a number of improvements.  Anyhow, I am very happy with my machine and use it both as a miller and a drilling machine. So, I have the best imaginable co-ordinate drilling machine and a very good milling machine all in one. "Dübendorf" is, by the way, a little village near to Zurich close to where I live.
That such co-operation between manufacturers should have existed is no surprise, the versatility and convenience of this style of miller having spawned many other European-made copies* with some identical but others developed, refined and enlarged. One machine with which an interesting comparison can be made is the German-built Maho, a miller not as popular as the Deckel in the UK, but widely employed in continental Europe.
The basis of the Prvomajska/Macmon was a cast-iron column surmounted by a sliding housing that could be driven backwards and forwards by a handwheel positioned in the top right-hand corner of the column's right-hand face. The handwheel (like all on the machine) was fitted with a very large-diameter micrometer collar and the feed screw protected by a bellows. The housing contained a hardened and ground spindle, with a generously-large 40 INT or 4-Morse spindle nose, running in two-row parallel roller bearings of the precision NN type (with an adjustable clearance) at the front and a special two-row angular thrust SKF bearing at the rear. Fastened to the middle of the spindle was a gear that engaged with - and slid along as the head position changed - a long gear beneath it. The drive gearbox, built into the top of the main column, held hardened gears, ground on their flanks, running in a splash oil bath. 16 spindle speeds (40, 63, 80, 100, 125, 160, 200, 250, 320, 400, 500, 630, 800, 1000, 1250 and 2000 r.p.m.) were available powered by a large-frame, 2-speed 1.4/2.3 kW 700/1400 r.p.m. motor and controlled by a combination of the juxtaposition of two levers on the right-hand face of the column and electrical switches.
Three heads were available, all gear-driven and mounted on top of the sliding housing: a standard vertical, a high-speed vertical and a slotting attachment. The standard vertical head had a 360-degree swivelling front section holding a 70-mm travel quill operated by a quick-action lever. Driven at a 1 : 1 ratio the head had the same speed range as the horizontal spindle. The high-speed head (normally a very desirable extra on this type of miller), would have disappointed the skilled operator looking for precise control of the cutter through a fine-feed mechanism: the head was simply a motorised adaptation of the standard unit with the same relatively short travel, lever-action quill - though as some compensation  its longer mounting arm did give it an extra 140-mm of reach and its four speeds spanned a useful 1200 to 6000 r.p.m. The hardened spindle was driven by a V-belt and fitted with a special adaptor to take collets (Maker's Part 03-06-V16) with shank sizes of 4 to 12.5 mm.
A developed version of the ALG-100 was also sold, the ALG100B. This model is instantly recognisable by its full-circle handwheels and the absence of electrical controls on the right-hand face of the main column. Although both the layout and general appearance of the two machines were, at a glance, almost indistinguishable the 100B incorporated numerous modifications in the search for better performance and reliability.
*Proof of the type's success - the genus Precision Universal Milling Machine - is evident from the number of similar machines made in various countries including:
Austria:
Emco Model F3
Belgium:  S.A.B.C.A. Model JRC-2
Czechoslovakia:  TOS FN Models
England: Alexander "Master Toolmaker" and the Ajax "00", an import of uncertain origin.
Germany: Hahn & Kolb with their pre-WW2 Variomat model
Wilhelm Grupp Universal- Fräsmaschine Type UF 20 N/120
Hermle Models UWF-700 and UWF-700-PH
Leinen Super Precision Micro Mill
Macmon Models M-100 & M-200 (though these were actually manufactured by Prvomajska); Maho (many models over several decades)
Ruhla
Rumag Models RW-416 and RW-416-VG
SHW (Schwabische Huttenwerke) Models UF1, UF2 and UF3
Thiel Models 58, 158 and 159
Wemas Type WMS
Italy: C.B.Ferrari Models M1R & M2R
Bandini Model FA-1/CB and badged as Fragola (agents, who also sold a version of the Spanish Meteba).
Japan: Riken Models RTM2 and RTM3
Poland: "Avia" and "Polamco" Models FNC25, FND-25 and FND-32 by Fabryka Obrabiarek Precyzyinych
Russia: "Stankoimport 676"
Spain: Metba Models MB-0, MB-1, MB-2, MB-3 and MB-4
Switzerland: Aciera Models F1, F2, F3, F4 and F5
Christen and Perrin Types U-O and U-1 (Perrin Frères SA, Moutier)
Hispano-Suiza S.A. Model HSS-143
Luthy
Mikron Models WF2/3S, WF3S, WF-3-DCM & WF-2/3-DCM
Perrin Type U-1
Schaublin Model 13 and Model 22
The former Yugoslavia: Prvomajska (in Zagreb with Models ALG-100 and ALG200)
Sinn Models MS2D & MS4D
"Comet" Model X8130, imported to the UK in the 1970s by TI Comet.
United States: Brown & Sharpe "Omniversal"
Sloane & Chace in the USA produced a miniature bench version and at least five Chinese-built models have also been made, including one from the Beijing Instrument Machine Tool Works. A number of the "clones" merely followed the general Thiel/Maho/Deckel concept whilst others, like Bandini and Christen, borrowed heavily from Deckel and even had parts that were interchangeable. Should you come across any of these makes and models all will provide "The Deckel Experience" - though you must bear in mind that spares are unlikely to be available and, being complex, finely-made mechanisms, they can be difficult and expensive to repair..