This is a broad category of RepStrap that is build from "whatever I had laying around" + "as little purchased as possible".
It's the extremely budget-conscious version, for those with lots of time, and less money.
Essentially, it's a case of:
Build a 3-Axis table
- Out of whatever you've got lying around. Wood, Steel, etc.
Locate 2nd-hand steppers
- big old dot-matrix printers are a good source of these. (especially A3 or larger, with perforated paper feeders)
- some modern printers and scanners also have steppers in them
Stepper Motor Drivers
- if you can re-use some of the circuit/s from inside the printers then great (uln2003 are one common usable part)
- otherwise the sanctioned drivers are great: http://reprap.org/bin/view/Main/Stepper_Motor_Driver_2_3 Stepper_Motor_Driver_2_3
- another popular driver is the Pololu A4983 stepper driver carrier
Build an extruder
sound simple, but isn't for many.
- You can make a wooden one, or plastic one from blocks bolted together, and a little milling. patience is a virtue.
- or something similar to http://www.reprap.org/bin/view/Main/ThermoplastExtruder_2_0,
- or a laser-cut one: http://blog.reprap.org/2008/11/ive-put-instructions-up-for-assembling.html
- you might like to get some machine parts from here: http://forums.reprap.org/read.php?94,18969,page=3
- Or have a look at hotend or Hot_End_Comparison
Here are links to pictures of a couple of junkstraps: