So in preparation for a timing belt job I made this tool since I didn't buy one and took some pictures/measurements along the way.

Required stuff:
Some 3mm drill bits/pins of some sort
a piece of mild steel
a grinder
Welder is good to have
a drill
~13mm nut/bolt

Start by making a rough cardboard outline of your tool:



Trace it on a piece of steel:




I already drilled my holes for the pins.
The holes should be ~13mm apart

Grind a relief for the tensioner bolt.




and after some cleanup and grinding it to correct size:



Tack your pins in the holes



Note that you don't have to weld them if you don't have a welder. All you have to do is get them to stay in place with epoxy/whatever

Cut the pins flat, add some weld and grind them a bit nicer:



again you can just use epoxy or something if you don't have a welder.

For the tension nut/bolt you can either weld a nut in there or do what I did and drill and tap a bolt in there:



and from the other side:



Here are the final dimensions of my tool with some beautiful ms paint:


The pins protrude ~6mm on the other side.


Cheers :3

 

I made the rod portion using all thread but i couldn't justify spending time making that tool when i had this available for $10 on amazon.