Any percussion clamp that holds a 3/8" rod will work.
Place Your Miller Machine, Anywhere, In Any Setup
I've made some mount suggestions below.
LP Percussion Bracket
This is the one I imagine most players already own.
I've used this one the most.
Model LP236C
Meinl Multi Clamp
This is the best deal among all the mounts listed here.
Very similar in design to the LP model above.
Model HMC-1
Tama Universal Clamp
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
Setup Tip
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.
LP Claw
The LP Claw is great 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
Pearl Quick Release Clamp
This Pearl mount is great when you want to mount two Machines close together.
The clamps are quick release so it's easy to setup.
Model ADP30
Grover Pro Multi-Stand Adapter
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
Setup Tip
If your triangle seems too big try mounting the Machine Body below the mount, like this.
LP Mini Everything Rack
Similar to the Pearl mount above, the LP Mini Everything Rack, is great when you need to mount two Machines close to each other.
Model LP472
Tama Multi Clamp
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
Tama Compact Clamp
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
Another Option?
If you've got a mount that you like, let me know, I'd love to check it out.