Even if you don't have a laser cutter you can still make many of the TurtleBot parts with basic hand tools.
First, cut a 12.75"x12.75" piece of 1/4" MDF
Setup a compass with an opening of 6.2" to create a 12.4" diameter circle.
From each edge of the plate draw a small arc to find the approximate center.
Print out the TurtleBot plate at a 1:1 scale to use as a drill template.
A coping saw or a scroll saw can be used to cut out the circular shape from the MDF.
After you have cut out MDF, attach the template and start drilling.
If the holes end up misaligned you can drill them a little larger and use a washer if necessary to make things fit.
If you get tired of drilling and sawing, you can buy laser cut discs and other TurtleBot parts here.