We use reversible bumpers that change colors without removing the bumpers from the robot - it takes about 10 seconds to flip the fabric up or down and secure it with velcro. It's designed to the 2014 game rules (because bumpers weren't required in 2015 and the 2016 rules aren't out yet), so be sure to check the new rules.
This
PDF, CAD model and drawing has all the information needed to make them, and the CAD is designed to be
very easy to edit in SolidWorks: change two assembly cuts (see PDF) to make it fit your robot width & length (and adjust or suppress a third cut if you need clearance for part of your robot).
It includes a STEP file for importing into other CAD packages, and it's simple enough that you could probably skip CAD and just tweak the dimensions on the PDF too. The PDF includes sources for the fabric, pool noodles, and hardware.
The weights for the materials in the SolidWorks file are accurate - about 14.4 lbs (without the cutout) as designed for a ~27" x 28" robot.
I guess true innovation is when you can actually harness physics to do what you want. Heck -- that sounds suspiciously like engineering. - JVN [more] 
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