DIY to the rescue.
What you'll need:
a pair of scissors**
make up remover/water
* I'd highly recommend using a GWP mascara for this (especially since they are free!). The brush/wand should be slightly pointed at the top and should be the non-plastic variety. I'm not sure what it is made out of, possibly nylon?
** I'd recommend cuticle scissors or something similar. These huge ones were awkward!
Step 1: Remove the wand from the container and clean it!
TIP: Use slightly harder paper towels so they don't leave little bits on your wand. If you use waterproof mascara you'll have to use an oil based remover, plus soap and water to clean it.
Step 2: Take your scissors (again I recommend smaller scissors especially if you are using GWP mascaras) and start cutting the fibers on all sides of the brush, coming as close to the actual wand as possible without puncturing it. Do this over the trash can or plastic bag.
TIP: Keep on snipping until you get to the desired length. I'd recommend using a piece of tape as a guide if you want it exact.
Step 3: Clean the wand again to ensure there aren't any hairs that weren't attached but had hidden their way into the wand.