Splinter - Yes, the rotary cutter is like a pizza cutter. Mine is probably due for a new wheel, but it's still working pretty good. I like your approach to the process. I did consider doing the reverse pattern to avoid the extra steps, but thought I'd likely mess up trying to assemble the pieces as a mirror image. If I'd spent more time considering that option, I would have realized I could have printed-out a reversed pattern sheet. Oh well, there's always next time. But given your description of the shelf liner, I will consider switching over to that method for some of the assembly. It will definitely be easier to peel-off than the blue tape.
Dutchy - Yes, there are definitely similarities with Mondrian with the primary colors and geometric shapes.