Any clamp that holds a 3/8" rod will work.
I've made some suggestions below.
This is the most common mount I imagine most drummer/percussionists already have.
I've used this one the most, in many setups.
Model LP236C
This is the best deal among all the mounts listed here.
Very similar in design to the LP model above.
Model HMC-1
This mount is easy to attach to a cymbal stand and gives you the option of changing the angle.
Uses the Tama FastClamp Easy Set Up System.
Model MC56
Try positioning your Machine so the mounted beater is perpendicular to your stick. This gives you the most surface area to hit, and increases your accuracy.
The entire Machine can be hidden behind a music stand, or perhaps a cymbal... all you need to see is the red striking surface.
The LP Claw is great to use when you want to mount your Miller Machine on the rim of a drum.
I've used it to mount my Finger Cymbal Machine on the floor tom.
Model LP592X
This Pearl mount is great when you want to mount two Machines close to each other.
The clamps are quick release so it's really easy to setup.
Model ADP30
Here's a great option for mounting your Miller Machine directly onto a cymbal stand.
This adapter is small, easy to pack, and makes it super easy to place your Machine anywhere in your setup.
Model GRO-PW-MA
Similar to the Pearl mount above, the LP Mini Everything Rack is great for mounting two Machines close to each other.
Model LP472
This clamp gives you lots of adjustment options.
It's a bit more robust than you may need, but I like it when I want my Machine mounted in a very specific spot.
Model MC66
This one is small and works great if you are in a tight space.
Just be careful, your Machine will be closer to the stand, make sure you have enough clearance to hit the beater.
Model MC7
You can use most anything to play the Machine.
In the Broadway Production of The Addams Family, I had a solo triangle cue that I played while sitting in a chair, pretending to read a book.
With the book held high, blocking my face, I could see the Machine on my left side, but to the conductor (on my right) it looked like I had my face in the book.
I was pretty far away from the Machine and used a 6 foot long piece of dowel to hit the beater.