I need a chain adjustin tool 4 my NC30 but im skint so i wanna make one at work and see if it will do the job well enough to save me spendin out cash, and the money i save can go towards a new BT92 Battlax :D cos my rear at the moment has 2 dirty screws in it!!

If anyone would be kind enough to measure the tool and post up the measurements i would appreciate it a lot!! The most important measurement is the inner diameter of the curved part, and an approximate no. of degrees between the handle and the tooth thing at the end.
Im an apprentice at airbus UK so can get my hands on aluminium, was thinkin i cud rivet a couple of 18 or 16 SWG aluminium pieces together and perhaps sort a wooden handle for it.
Anyone got any suggestions for materials, or even better, a spare tool, then please let me know, haha.
Thanks
Dan