INTRO
It seems to be the month of construction sets on Thingiverse, so here is another entry in the category.

Contraptor is a DIY open source construction set for building Cartesian robots. It is basically 1" aluminum Erector set with linear motion extensions. While it's in development and sometimes things don't work as they should, functional robots have been assembled from it: http://contraptor.org/contraptions

The set is designed to be made with the simple tools of a basic workshop. A lot of materials for Contraptor like aluminum angle, threaded rods and fasteners can be found in a hardware store. In the spirit of modularity, it uses Makerbot/Reprap electronics and Arduino/Sanguino controller.

In addition to DIY plans, we're working on Shopbot-able kits that can be manufactured in small quantities by anyone willing, from open source drawings.

Contraptor components and assemblies are modeled in Sketchup and are hosted on Google 3D Warehouse, mostly for ease of accessing from within Sketchup. Thingiverse is the best place to host DXF/SVG sources and part lists for components, so there will be more Contraptor things coming (hopefully including printed ones from the community :).

Apologies for the long read, on to the thing:
/INTRO

Perforated angle comes in lengths from 1" to 24" and can be used as a structural component, as well as a linear motion rail for sliding elements. Attached DXF file and part list are for 1-ft long perforated angle.

Sketchup source:
http://sketchup.google.com/3dwarehouse/search?q=contraptor+angle

Aluminum angle stock is center punched with Starrett 819 automatic center punch using pegboard as a guide. Guide holes for attaching angle to pegboard are made with the help of the template (SVG file), paper and scotch. Once center punched, the holes can be drilled on demand. Countersink bit deburrs the holes nicely.

Detailed howto and more ways to make perforated angle:
http://www.contraptor.org/make-perforated-angle