I took some more photos for clarity on what it is. I built this for a few reasons: #1: to build my face-frame I had to rip-cut my strips from 1x4's and 1x6's. #2: I had to take those more narrow strips and cut them down to the correct length. #3: I'm using a circular-saw and for this to cut vertically without tilting it needs to be fully supported on both sides.
These three problems aren't an issue if you have a table saw or other such large item like a miter saw (etc) - which I don't have.
In this picture the jig is flipped over so you can see how it's constructed. Two 8' 1x4 strips are spaced apart which forms a 1-1/2" "cutting channel" in between. These 1x4's are held in place by a series of plywood strips - it's all screwed together.
In this photo the far-end of the jig is the 'rip-cutting end' and the end at the bottom of the photos is the 'L-shaped channel cutting' end:
At the far end in the previous photo is the rip-cutting end:
The space between the two 1x4's of the jig provide a channel for my saw blade to glide through - the piece that is to be rip-cut lays on top and butts up against the rip-stop end. Using this setup I can rip-cut very narrow pieces - something that was challenging without the jig.
Rip stop end:
Board to be rip-cut. I've highlighted the rip-cut line in blue - this sits over top of the 'cutting channel' to allow the blade to freely move through without destroying my jig in the process.
The rip-stop affixed to the end is shorter than the boards I'm cutting so it acts as a support but does not prevent the saw from moving forward.
The opposite end of the jig makes use of the open-end of the 'cutting channel' - the long piece that sticks out forms an "L-shaped cutting guide" for my visual use when using my saw.
I draw a cut-mark on the piece to be cut and set this piece in the "cutting channel" - with the penciled cut mark lining up with the end of the jig.
Then I can set the saw in place and use the measurements on my saw-house to follow through with my cut - two photos of this (before cut, during cut.)
The wood I'm cutting in this picture is the same thickness as the 1x4's - so the surface is flush and flat which prevents my saw from snagging and 'jumping' when I cut.
Here you can see that I'm using the protruding "L-shaped cutting guide" to continue through with my cut when the penciled in line is no longer visible.
Most of the time when using this L-shaped cutting end I didn't have my saw flush up against the jig like in these photos - I was able to space it away 1/8" (or however far I wanted) by using the measure-guide on the front of my saw house. . . which helped me spare my jig from getting nicked up.