I recently bought a GSI Cascadian mug and one thing it's missing is measurement graduations. BPL has a review of the cup which apparently does have measurement markings on it. Does anybody have any ideas as to how to mark the inside of the mug with 1/2 cup, 1 cup, etc? It's not quite translucent enough to see the liquid level from the outside so I can't mark the outside. It's made out of polypropylene so a regular magic marker probably won't stick and might be toxic anyways. I was thinking of melting lines in it with a soldering iron or touching it with a dremel grinding wheel to carve a slight groove. Neither of these would be a good contrast. Thoughts?

A light touch with a Dremel is what I would do. I mark my cheap aluminum pots that way. How many oz does it hold? 12? If it's that small of a cup then why not just eyeball the measurements?

Another idea is to mark a utensil instead of the pot: place the utensil in the pot (usually at a diagonal) add water in desired increments and draw a line on the utensil . In the field, repeat the process and use the lines to match the desired volume.

That's a good idea. Just have to remember which utensil goes with which pot. (-:

I have used a Sharpie to mark mine (let it dry well after marking) but it will slowly fade over time. I have also used a diamond awl to scratch marks in some. I mark them at 1-1/2, 2, and 2-1/2 cups.