I like to use disposable paper cups for mixing epoxy. They're cheap at $6 for 250 cups, and I don't have to worry about cleanup. (Make sure you get wax-free cups) Although I use epoxy pumps to meter my batches, I like to verify the ratio by using a calibrated mixing cup. Here's an easy way to turn one disposable cup into a reusable measuring gauge. Variations of this technique have been discussed on Guillemot Kayaks Building BBS and many people are responsible for the idea.
Start by taking one cup and cutting a window in the side. Make it about an inch wide and extending from the very bottom of the cup to near the top. It only needs to be a little taller than the level of the largest batch of epoxy you intend to mix.
Drop a second cup inside the first. Using a small measuring cup to fill the inner cup with water in equal increments. I started with 1/2 oz. Then place a mark on the outer cup at the level inside the inner cup. Continue to add water in measured amounts, marking the outer cup after each. Now, when you meter your epoxy, place a fresh cup inside the calibrated cup, and dispense the epoxy using the marks as a guide. Then remove the measuring gauge and set it aside for the next use.
You may have to dispense the epoxy under a strong light to be able to see the level of the epoxy through the window of the outer cup. I keep a small flashlight near the epoxy jugs for this purpose. This is the one flaw in using paper cups. If you use clear plastic cups, you can use the same marking technique and be able to see clearly the level of epoxy.
(Note: Since you're usually interested only in the ratio of resin to hardener, your level marks can be of any arbitrary units. So, when making the measuring gauge, if you don't have a cup with calibrated markings, it is sufficient to just use equal volumes. Pour one in, and mark 1, pour a second, mark 2, etc. When measuring epoxy, you'll still be able to verify correct ratios)
-Ross