You can make perfectly good slits using nothing more than a hacksaw. If you need wide slots you can load two blades in the same saw. i know that hand tools have passed out of fashion but they still have their uses, and often are the quickest way to achieve an objective.
Regarding the cam lobe measurer, I feed the rotary and linear encoder outputs into an Arduino for decoding and then pass it on to a Laptop via USB where it gets processed and plotted in analysis software that I wrote, which also combines it with flow bench data.
In the 70s and 80s I had a business in the UK making bike chassis, many of which have won championships around the world. Since the late 80s i moved to live in Spain and since then I have not done any physical construction for others, finding it easier to tell others how to. In other words I became a madam. So I turned to writing, doing seminars and developing software etc. You can see more of my history and activities by looking at the following links in addition to a few posts that I have made on this forum, Homemade Tools built by tonyfoale - HomemadeTools.net . Although I seem to have gained the reputation as the chassis guru it has always been engines that have been a stronger interest.
TONY FOALE DESIGNS - Home page
Making stuff and having fun.