THE DOCUMENT HAS ALL THE INFORMATION OF THE ASSEMBLY OF SOLID WORK RELATED TO PROJECT U WILL FIND ALL THE INFORMATION IN APPENDIX OF DOCUMENT THAT I HAVE SHARED ABOVE THAT WILL HELP U A LOT IN MAKING THIS
First of all this is not a discussion group on CAD so I do not care what software he chose to create his document about a stair climbing machine.
The choice of materials depends on the actual market being considered. I could care less what material is chosen to build a prototype as presented in the document. It is obvious that he employed many stock items, used an available 3d printer, and simplest machines to fabricate parts. The choices would be totally different for a mass produced machine even for a niche market. I didn't in scanning his document see this as an important topic. Again I really do not care.
Didn't see the machine climb a spiral stair case because the two sides are not independent in his model. Some niche markets may include traveling on the ground which would require independent suspension of the treads. Also he assumed only motion in one direction. The machine can not back down.
So how could this be attacked with a minimum of components is to put the center of mass at the hing point between the two tracks.