The great thing about open source is there is tons of information online and with a google search you can find all the information you need, I will go over a few basic items but there is so much information that is so well documentetd it wouldn't make

Making the slides: One of the ways to lower costs is to get rid of the steel rods and bearings, you can still use steel rods and lm8u bearings in the pvc frame with a fitting called a cord connector if you want to: http://www.homedepot.com/p/Halex-1-2-in-ACC-Non-Metallic-Strain-Relief-Cord-Connector-27693/