Super Quiet DC Motor?

I’m looking for an extremely quiet DC motor to run at 9V but low RPM. I’ve tried some Pololu motors and a Sayama one that’s quite common, but both are too loud for my project (the motor is going to sit inside a plastic model kit and spin a hemispherical dome).

Any suggestions? You can see my WIP of the circuit here:

Forgot to mention - the motor needs to be roughly the same size as the Sayama.

Could you use a stepper motor? There are some small stepper motors that are pretty quiet.
That will get rid of the gear box noise, but you will have less torque compared to a geared motor.

Thanks jwatte. I don’t need a lot of torque since it’s just spinning a small plastic hemisphere but I’m more worried about having a stepper motor just spin continuously as opposed to its normal use of discrete steps (I have to admit, I haven’t worked with stepper motors before so I’m not that familiar with them).

If you step a stepper motor at a consistent step rate, it will be spinning continuously.
Stepper motors are used for all kinds of things that rotate or travel, movement can be very smooth.
Easiest is to use a controller, and tie a PWM output to the controller to generate the step pulses; vary the PWM frequency to vary the speed.