3d_dobsonian_square_tube_telescope
The program one would use is the following called OpenSCAD
The Linux/ Windows/ OS X download page is below
http://www.openscad.org/downloads.html
Once the software is installed click the 'open' button and point to the .scad file. This will import the design.
Then once one clicks render icon (if one hovers cursor above any icon, it lists the function), it will take a few minutes to render and create 3D version which one can rotate or view with their mouse.