The RepRap is an additive Rapid Prototyping machine built from simple parts and electronics, and is designed to be (mostly) self-replicating in that it will be able to create many of the parts required to build a copy of itself.
Here is a photo of one (this is not mine, it's copied from the RepRap Wiki)
The basic philosophy of RepRap is that it will be something that's easy to build, can be created with parts that are relatively easy to acquire, and can be had for much less than commercial solutions, which usually start out around $15,000.
So to begin, I will be making the Mendel version, which is the second (real) version of the unit. Darwin was the first, and used a cube-like structure, while the newer Mendel version uses a triangular prism shape. It also trades four lead screws to control the bed for two, making things simpler and giving the motors less to drive. Power consumption is a large factor in design decisions, as it seems most people are trying to keep the current draw low. This may be to enhance portable possibilities, such as running it off of a battery or solar panel. It would be pretty neat to be able to just set a panel facing the sun and hit a button, and let the unit start to work on a part, if the power drops too low it will pause and wait until it has enough to continue.. and eventually you'll get a fabricated piece! Perhaps that'll be my contribution, who knows!
Either way, I need to start getting the parts together. The RepRap Parts Lister seems to be somewhat out of date, so I will be using a Google Spreadsheet to list all my parts, locations, costs, and amounts, which should help anyone building a Mendel with finding the right items while being sure they'll work with the new version. It will also allow me to share it in realtime, which should help keep things up to date on this blog.
Here's the link: RepRap Parts BOM
I will most likely post this up somewhere on the RepRap forums so that people there can help see how wrong I'm doing things and hopefully steer me towards the right direction, but for now, I'm on my own.