CNC level of accuracy needed without CNC machine:

[inland imp]

I want to build a large wheel for cats to run in. I want the inner diameter to be 1 meter and have enough 12mm Baltic birch plywood BUT not a single sheet that is large enough. I need two rings and thought I can make it using interlocking pieces BUT I do not have a CNC machine. I do have a table mounted router and access to a lasercutter that can cut up to 6mm plywood without a problem. I designed this piece and can cut it as a template from 6 mm plywood. I have a jigsaw and can roughcut the 12mm pieces with a few mm overhang and then use an flush trim bit on the router to get it exact (the inner curves of the round parts are larger than the outer bit). Is there any reason why I should not do it this way? I want a really round outer dimension as this will run on wheels and inaccuracies will make not run smoothly. Any other comments or suggestions?

The interlocking parts look like this closeup and is approximately 26cm in length:

[livid epoch]

It depends on whatever else you've got going on for structure. I've never created a cat wheel like this; but, I'd be worried about those joints not being rigid enough. If it were me, I would laminate overlapping pieces of plywood to get to my desired thickness.

Also since really you just need the outside to be smooth and round you could leave the outside edge wide of your line and then use a trammel and router to get it perfect after assembly. Personally I would do this regardless of my joinery.

[inland imp]

I have a lot of 340x120x3mm plywood offcuts from other projects and was planning to lasercut a second set of interlocking parts from this (one set for each wheel). The holes are spaced exactly so I can overlap these with the 12mm pieces and use 4mm dowels as during assembly (the holes would also serve as the attachment points during the initial routing and thus everything would register to the holes) - so overlapping is part of the plan both for accuracy and a bit of strength (although the plywood joint is almost stong enough to hold me and I am much heavier than a cat). I did consider routing the outside edge after assembly but are a bit worried that I cannot centre it perfectly. But I will give it a bit more thought.

[vagrant nebula]

I imagine a ton of work and the cat noping out on it all together. 😂

[inland imp]

I have 3 cats - which just means 3 times the disappointment