Router Circle Cutting Jig for Makita RT0700C and it's clone Zinsano TM-635ST
Use hex head bolts M5 and nuts.
You can use rounded heads too, but need to make two flat sides.
For the handle it's better to use M5 threaded shaft with two tight nuts, so you can change the length of the bit easily.
With the extension, you can do it as long as you need.
There is two shorts parts because some radius are not possible otherwise.
If you need to mod it, no problem f3d file is included !