As the title says I need some kind of "Nunchaku Crafting Delta Force"

Here is my problem:
I bought a wooden block, dimensions 22 x 22 x 5 cm. I wanna make several pairs of chucks out of this block, but I have some serious problems with accuracy


the upper "thing" on the picture above is the block, the red lines are where I want to cut it (or already did)
The prob is now, that the sawed off parts are kinda crooked (the lower thing in the picture)
The more I try to fix it the more I mess it up, I was hoping someone of you could help me with this.
I need to get all sides of the square stick equal, so if anyone has an idea to make it fast and accurate I would really appreciate it

Of course, accuracy is more important than speed

I hope I could explain what I mean
