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We are starting a project to build and maintain a 3D printer. At the moment we are discussing which model we will focus on. Here are some options:

RepRap

RepRap Prusa Mendel (Taken from Wikimedia user Julianh72)
Model: Mendel
Version: Prusa

The RepRap seems to be a promising, affordable and flexible, adaptable candidate. Especially the RepRap Prusa Mendel seems to be well suited for a Hackerspace. It costs between 450€ and 800€ as a ready set and probably less than 200€ if we get the parts locally.

The parts needed for the Prusa Mendel are almost entirely standard parts that can be found in almost any hardware store. These are mostly M8 thread rods, M8 screws and nuts, standard skateboard bearings, the common NEMA 17 stepper motor.

Here's a list of the parts needed (taken from the RepRap Wiki)


Required
Quantity Description Type Comments
83 M8 nut Fastener Buy a 100-pack to be on the safe side.
93 M8 washer Fastener Buy a 100-pack to be on the safe side. (Grade 2 works fine.)
6 M8×30 mudguard / fender washer Fastener These are also known as penny washers, they have a much larger outer diameter than regular washers.
2 M4×20 bolt Fastener To mount the extruder
2 M4 nut Fastener To mount the extruder
2 M4 washer Fastener To mount the extruder
22 M3×10 bolt Fastener
16 M3×25 bolt Fastener Or eight M3×25 bolt plus eight M3x20 bolts. The M3x25 bolts are too long for the recent Prusa z-motor-holder and rod-clamp, and also for the Z motor couplings. See Section 8, steps 4 and 13 for details.
4 M3×40 bolt Fastener
70 M3 washer Fastener
40 M3 nut Fastener 8 optionally locknut / stop nut / nyloc
2 M3 grub screw / set screw Fastener M3x8 seems about ideal but anything 6mm or longer should do. If these are hard to get, additional M3×10 bolts will do the job instead.
3 608 roller skate / inline skate / skateboard bearing Bearings You don't need to ask for a "608 bearing" at a skate shop, just ask for wheel bearings.
4 ballpoint pen springs Spring To fit over M3 bolts. Ballpoint pens are a common, cheap source of suitable springs. They are about 25mm long and compress to about 10mm.
6 M8×370mm Threaded rod 3 per side

Note: The threaded rods can be cut from larger 6x1m pieces (see Threaded Rod Cut Order below).
4 M8×294mm Threaded rod front / rear
3 M8×440mm Threaded rod top / bottom
2 M8×210mm Threaded rod Z-leadscrew
1 M8×50mm Threaded rod or M8x30 or longer bolt for X idler. Take care: if the bolt is too long, it may not be threaded along a sufficient length
2 8mm×420mm Smooth rod X-bar

Note: 304 Stainless Steel, A2 Tool Steel, or O1 Tool Steel are recommended for smooth rods as it can help to prevent friction from rust and manufacturing (straightness) standards are higher. Rust issues can be prevented on the normal steel rods by maintaining a coat of oil. The smooth rods can also be cut from larger 3x1m pieces (see Smooth Rod Cut Order below).
2 8mm×406mm Smooth rod Y-bar
2 8mm×350mm Smooth rod Z-bar
1 225mm×225mm print top plate Thick Sheet
1 140mm×225mm print bottom plate Thick Sheet Note: The Prusa Iteration 2 design does not use a print bottom plate.
1 840mm×5mm T5 pitch timing belt Belt Y axis
1 900mm×5mm T5 pitch timing belt Belt X axis
5 NEMA 17 bipolar stepper motor Stepper Be sure to get ones with at least 20mm of shaft length. Shorter shafts require modifications to the X pulley assembly and Z motor couplers. One of the five motors, for use with the extruder, should be capable of creating a holding torque of at least 40Ncm, at the very least.
50 small cable binder / ziptie Misc
1 Wade's Geared Extruder for 1.75mm filament RepRap Universal Mini Extruder; or any other compatible extruder for either
1 Electronics + endstops This can be RAMPS, Sanguinololu, Generation 6 Electronics, Generation 7 Electronics, Generation 3 Electronics, or any other Mendel compatible electronics. End-stops are either optical switches or micro-switches (Recommended), and you need three, one for each of the X, Y, Z axes.