I made a simple circlar saw guide with a small timber(15ｍｍx30ｍｍ)
No special tool is necessary, a handsaw and drill are the only tools you will use to make this.
FIY: I used a finish nailer to attach timbers in the video, you can use any screws instead.

Jig plan convenient for woodworking
[Plan List]
https://jsk-koubou.stores.jp/