what arduino to buuy

hello, I'm new to this forum and new to arduinos too.
I am looking to build a massage device using a push / pull solonoid. To create a sinusoidal sign wave out of the solonois I have been recommended to buy a Arduino.
Can anyone offer any advice please on a potential unit to buy.

I'd recommend you a Starter Kit, where you can get familiar with the Arduino and the different peripheral devices. Using solenoids requires some electronic experience as well. But perhaps a massage device will work with servo or stepper motors as well, using ready made components.

I was not aware that a solenoid could be be controlled in such a manner and with any power.

an UNO, like all Arduinos , NANO / Mini / Mega have PWM output.
it would seem that you need the PWM output, so it seems that any one would work.

also, since you need to test your theory, the UNO offers the most versatility, if only because it allows the use of plug in shields.

push / pull solonoid. To create a sinusoidal sign wave out of the solonois

Solenoids are not typically variable position devices, so you might want to look at this part of your project first.

Massage machines are done with linear actuators (ie, gear reduction motor driving something that moves in and out) and normal motors driving kneady mechanisms

So you would be varying the speed of the motor. The software and pin demands sound small, so any '328-based arduino is a good choice - the Uno or a clone thereof is what most of us start with, and the most widely used and has the best compatibility with Arduino libraries and online resources.

thank you folks for all of you're replies and shedding some light. I have an electrical wiz that is assisting me on the build with this machine. The plan is to use a TENS machine or interferential machine with pre dialled in wave shapes/widths/sinual soidal. Up untill now I have been using geared motors and CNC machined cam shapes to create varied wave forms.
Can a arduino be programmed to create varied wave form?
thanks again