This is an quick and easy-to-make alternative to buying a GPS carry case or cover. It only took me about an hour or less. The only supplies needed are: scissors, needle & thread, and a koozie. Optional: velcro to attach to open end so that your GPS won't fall out.
Step 1: Get a Koozie
Finding a koozie should not be difficult since pretty much every business gives these away free all the time. The best one to use is a water bottle sized koozie since it will cover the whole GPS and will have room to sew the end.
Step 2: Cut the End Off & Turn Koozie Inside Out to Sew
Cut the bottom off the koozie (if it is way too big, you'll need to cut off about an inch or two from the end while making sure there is ample room for the GPS to fit inside...but not too much so it will stay still inside there). Turn the koozie inside out & sew a chain stitch (looping over to close the gap).
Step 3: Finish!
Now you are done! If you want, sew velcro on the insides of the open end of your GPS case so your GPS won't fall out!
Another fun feature: My koozie happened to have a carabiner (the thing climbers use) attached to it so now I can clip my GPS case to my belt if I wanted to be super nerdy. You can add one of those to your koozie case, but you can figure that one out yourself :)