I have been using this type of saw blade guard for years, it's simple, cheap, durable and easy to use.
It is a piece of flexible fiber optic or electrical conduit.
Step 1: Materials
The flexible conduit I used was from dumpster dives (Free)
The Orange type (fiber optic use) is much more flexible then the gray electrical type since it is for interior use only, whereas the Electrical is for interior and exterior use.
You will need a sharp knife or heavy duty shears to cut the slot in the conduit.
Step 2: What the Slot Looks Like
In the photo where my fingers are, shows what the self closing slot looks like.
Step 3: On the Blade
The guard easily comes off the blade, turn the slot to the opposite side from the blades teeth and pull the guard away.
To put the guard on slide it on with the slot on the opposite side from the blades teeth and it encompasses the whole blade.
On hand saws it just slides on and off.
JUST a NOTE of warning hand saw blades can be very SHARP.