In addition I like to use this product because I don't need a saw of any kind, and no saw dust, I do end up with shavings that are easy to clean up.
All you need is a straight edge metal guide, rule, a marking pen and a Plexiglas cutter.
You can get a cutter like this one at almost any hardware store. As you can see this one is a little on the old side but still works for me.
Mark out the size you want, lay your straight edge guide on your marks, press down firmly and the drag the cutter towards you carefully following along the straight edge.
You need to make a few passes going both directions to insure you get to the edges at both ends of your cut before you attempt to snap it off.
Once done clean the edges with an emery board, I like to use the ones you would use for finger nails and now your ready to move on to the next step, mounting your objects to the new bases.
I like to sit down and cut most of my general sizes I use all at once, that way I have stacks of bases ready to use.
Other things about Plexiglas it will not warp takes glues and paint well, plus any left over sizes or odd sizes you can use for your buildings' exteriors or other objects.
This is how I base my small terrain objects and I hope you find this useful have fun gaming.