Blade guards can be essential in the above case to ensure that you do not cut your hand. However, they can be unnecessarily expensive (a quick Google search returned http://bit.ly/1bHZThw which goes for a whopping 5 bucks...).
This is a very simple guide to make your own blade guard using everyday household materials (or at least easy to obtain).
Step 1: Stuff Needed to Build It and Make It Happen
-Cardboard (cereal box works well)
Other ideas to make this include using twist ties, rubber bands, slit straws, etc. I chose this idea for its simpleness.
Step 2: Cutting & Fitting
A cereal box or cardboard of the same thickness works well.
Test fitted the piece to ensure that once folded over, it would cover the blade.
Cut, crease halfway, and trim of excess if desired.
Step 3: Stapling & Fitting
To make the hole, determine where the saw hole will end up once inside the guard, and use scissor point to poke a hole and enlarge if necessary.
Step 5: Finale