Quote structure pricing help?

I am hanging my single out there as a side gig. My clients are people who need CAD models of their ideas. Good enough to be 3D printed or presented to an investor. I have an hourly rate in mind but I wanted to provide three levels of approximate cost for the work. Projects range from relatively simple objects to perhaps ideas where the mechanism hasn’t been thought out.

Thoughts on what those three levels should be in terms of complexity? These three levels would just there to give a potential range to the client. I would still review and adjust the actual cost due to the amount of work required.