Building a hitting mat or platform for your Optishot is very easy and only requires a few basic tools.
First I went to a cheap home goods store that sells carpet and remnants. I was able to get this 5x7 turf for $15.99.
Next, I made a cardboard template of the Optishot. Be sure to include the part on the side where the wire goes in.
I then stood over on the turf to get an idea how big I wanted my mat to be and where the optishot should be.
I layed out the 1/2 plywood on the ground and cut it to about 4'x5'. I then then added 2x3's around the edges and at the seams. You could use any boards, I just happen to have extra 2x3's laying around.