Frame - laser cut 6mm Baltic birch plywood. We bought a 5'x5' sheet from Windsor Plywood - a Western Canadian and North Western US supplier of wood products. I used the "frame-6mm-colored-lines.dxf" design as a basis but narrowed the slots a little to make the 6mm ply fit tighter. You will need 6x 6-32 x 1" bolts and 6x 6-32 nuts to match. You could use 3mm or 4mm x 25mm bolts but we found the 6-32 a better fit.
Printed Plastic Parts - You will find them on eBay from various sellers. We had hoped to find someone local to print the parts for us but went with a set from eBay. If you want to get your own printed look under Josef Prusa's GitHub for the Prusa3-vanilla scad or stl files. You can also search Thingiverse for Prusa i3
Threaded Rod, Nuts and Washers - you will need approx 1 meter of M8 threaded rod and 1 meter of M10 threaded rod. Also 26 M8 nuts, 26 M8 washers, 12 M10 nuts, 12 M10 washers. These are for the frame Y-axis. We used zinc plated threaded rod from Fastenal - but you can find it at some hardware stores, AliExpress and eBay. You will also need 2 lengths of M5 threaded rod and 2 M5 nuts for the Z-axis. The minimum length we could buy was 1 meter. We first bought zinc plated 5mm threaded rod for the Z-axis but it wasn't very straight. The supplier told me this was typical of the cheaper zinc plated threaded rod so I looked for stainless threaded rod which was a lot better quality and very straight.
Smooth Rod - The design we used needs M8 smooth rod for the X, Y and Z axis, 2x 370mm, 2x 360mm and 2x 320mm. Quality straight rod is essential for good prints. We sourced them from BST Automation via AliExpress. You will also find sellers on eBay and local hardware stores. My mentor Rob tells me not to cheap out on the smooth rod.
LM8UU Bearings - These are the linear bearings for the bed movement on the Y-axis and the extruder/hot-end movement on the X-axis and the Z-axis. You will need 10 of these. Available from many eBay vendors.
Pulleys, Belts & Idler Bearings - The X and Y-axis travel each use a 20 tooth GT2 pulleys and approx 1 meter of toothed belt. We sourced ours from a local eBay vendor ibi-battery, but you will find them available from a lot of vendors. Also needed are idler bearings. Most i3 designs use either 608zz or 623 bearings. The 623 bearings are tiny and use printed guides which fit over them. You will see what I mean in later pictures.
Stepper Motors - You will need 5 NEMA 17 stepper motors. The NEMA 17 is a stepper motor with a 1.7" x1.7" faceplate. The RepRap wiki has quite a bit of info on them. My mentor Rob suggested this vendor on AliExpress - We had to buy 10 to get the pricing (but you have 5 to sell or use in your next 3D printer project). They are 1.2A which will keep the RAMPS drivers cooler, have approx 47N-m holding, are 1.8° stepping, 5mm shaft. If you are unsure then buy from a 3D printer vendor or check the RepRap wiki.
RAMPS 1.4 Kit - This consists of an Arduino Mega, a RAMPS 1.4 shield and 4 or 5 "drivers" The "drivers" control the NEMA 17 motors as their current requirements are greater than what an Arduino could handle. We sourced ours from SainSmart, but found a cheaper alternative on AliExpress Naturally you can find them on eBay too.
MK2A Heat Bed - As per the RepRap.org wiki article you want to be sure to get a good heated bed. We sourced ours from Botech Eng. There are a lot of other vendors listed on the wiki page. Make sure you get a 214mmx214mm size. You will also need a 3mm thick sheet of glass 8"x8" and blue painters tape or wide kapton tape.
Hot End - The hot end is another place not to cheap out. This blog article explains the difference between the original designs and clones. This RepRap.org wiki article has more info on hot ends. We went with this one from Makerfarm including the install kit.
Power Supply - You can use a PC ATX power supply, but we opted for a slim 12V power supply as it's smaller and I think it looks neater as it only has the necessary wires. Something in the 200W to 350W range should work. Check ebay. Also needed were a 115V plug with wires and some spade terminals.
Extruder - This was included in the printed parts we bought from eBay. It is a "Wades" style
Nuts. Bolts & Washers - You will need different length M3 bolts with washers and regular and nylock nuts. We bought M3 in 10mm, 14mm, 18mm, 25mm lengths. A bag of washers, a bag of regular nuts and a bag of nylocks.
Also M4 bots/nuts to bolt the hot-end to the extruder mount.
Wiring Kit - We bought a generic wiring kit off eBay. You will also need some heavier wire for the 12V connections. We bought a small roll or red and black stranded wire (16awg or 18awg)
Tools you will need:
Allen Keys for the hex bolts
Small sockets for the M3 and M4 nuts
Small adjustable wrenches for the M8 nuts
Long Nose Pliers
Heat Gun or Lighter for shrink tube