BushBuddy & nesting mug?

The little MSR titan mug will fit inside the bushbuddy but it will stick up out a bit. I do know that it will all fit inside a snow peak trek 900 pot with the stock lid.

You could always trim some of the top of a taller mug that meets your diameter requirements. I have trimmed quite a bit of Ti cooking gear. One may often modify a piece of gear to perform a particular job, or fit in a certain place. It's fun, if sometimes frustrating, and sometimes your ideas just don't work. I keep Ti scraps to experiment with.

I carry a Snowpeak 150 mL double wall titanium mug inside my Bushbuddy when I feel like having the luxury of a mug along with me.

The MSR Titan pot seems to work for me, and as Daniel points out it protrudes a bit. Not wanting to buy another piece of gear I just secure it with a stout rubber band to keep it all together.

Sam, thanks for the info regarding the SP 150ml dw mug.
Denis, thanks for pointing out a simple solution. Cutting down the REI Ti mug may work. Have to see if those silicone wrist bands would work to insulate bare fingers from the hot single wall mug. The fold old handles would have to go with a cut down.