Yes, I love Mardon's work, too. My current sidearm is modeled after the Marmit/Mardon's build up of it. But I have a question, I know the marmit has a lot of details in it, but what makes everyone think that the pistol (which barely has ANY reference pictures) is dead on accurate? I mean look at the other guns created for the OT. They were all based on real guns. The E-ll, Han and Luke's pistols, even Leia's guns were all based on and made from real weapons.
The Marmit gun just doesn't look like it is based on a real gun. Don't take my tone here wrong, but I just want to know why the general consensus us that the Marmit Fett is THE source to go to? Did they actually get the props to base their work off of, or is it just from pictures or something?
I mean the more I look at the other gun that Graeme was interested in, the more I see where they could've created his gun from it. Check out the attached photo I quickly through together. With a couple of pieces of sintra glued on the sides, and using the end from the spear, you could throw a halfway decent version of the ESB sidearm together out of that one.
I'm almost positive (as one can be with such limited knowledge and info) that the real prop was based off of a spear gun. Another correllation - look at luke and Vader's sabers. Both of the flash guns. Droid callers - flashguns. Look at at Fett with the various dental pieces strewn about. My thinking is they made a couple of sidearms for the Bespin scenes...Hey they needed a couple of guns...One is made outta a spear gun the other...could be.
I, by no means, think I have the "correct" gun base, but I wanted to try this little experiment out. Without more info, i'm going to try and match the Marmit's general layout, but with a real world base. Please keep the comments coming, they keep me thinking

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Graeme - I'll get the pics you wanted to see tonight after I do a little more work to it.
Nutcore - I'm not exactly sure. The round dot in the center of the grip it has "Equipo - Nemrod", but on the right hand side of the gun near the barrel it has "Fusil Oleoneumatico". Your guess is as good as mine.