I do the opposite, since I create multi-media with as many as 12
computer-controlled carousel projectors dissolving and flipping onto
a three-screen width in "retro-tech" (not "old-fashioned") production.

It is almost impossible to obtain 35mm slides of pipe organs and music
machines anymore.  And although I digitize many 35mm slides onto
computer-slide shows (a-la PowerPoint, etc.) it is almost impossible
to locate any affordable way to reverse the project these days.  I do
have a copy-board for taking second-generation images with a 35mm camera
for the Ken Burns sort of documentary, but it isn't the same as 35mm
resolution of the real thing.

I have several working computer systems manufactured by Clear Light
Industries that can operate as many as 24 projectors.  Also actuate
on cue some video projectors, 16mm and super-8 projectors and even a
vintage 4x4 projector onto my three 9' x 13' screens (or sometimes on
theatre screens or even blank walls at a shopping mall) -- dynamite for
my touring Christmas Carol multi-media 12-projector sing-along.

I have a couple of touring sing-along productions and several more in
storyboard at present, but I really need more slides to display my
museum history of the pipe organ and music machines.

Paul Kealy - Always looking for 35mm slides
http://stentorvox.com/