Breaking or losing the grill to your speakers can really expose your "sound" investments to all sorts of evils. This Instructable shows you one way to fabricate a new grill for your speakers.
The frame/grill needs to be fairly sturdy and be removable to access the speakers. It's ok if the frame takes some effort to get off after it's attached. You don't want it falling out unexpectedly.
I think the key requirement on this project is to use a single piece of plywood for your frame. Everything else is negotiable. A Negotiable Instructable - that should be a new category!
Step 1: Safety, Materials and Tools
At a minimum, ALWAYS wear eye protection and use hearing protection when power tools are in use (including your shop vac). A snug pair of mechanics gloves are a great thing to have around anytime there are splinters or if you need a little extra non-slip grip.
Materials: 1/2" plywood, black speaker grill cloth, medium duty staples, paint primer, black paint, small nails, Velcro, Legos
Tools: Tape measure, table saw, router with 1/8" straight bit, electric drill with 4" hole cutter, medium duty staple gun, 45/90 degree square, misc clamps, paint brushes