How to choose correct motor for my application?

I’m looking to play around with making a massage pad that I can lie down on and has massage nubs that are motor driven. There will be a motor that rotates the nub (the part that does the actual massaging) and motors that translate the nub in 3D "space".

I’m wondering if there’s a good way to choose which motors are appropriate for my application. I understand the difference between motor types but don’t know how to calculate torque required in this scenario. Perhaps there are other motor specs to consider too.

Thanks so much for any guidance you can offer!