If you can make it out to a specialty woodworking shop or a serious hardware store (not the average "home center"), you can get 2-part epoxy in separate bottles. It makes portioning and mixing far easier than the double-barrel syringes. I find the easiest way to get the same amount is to take the surface on which I'll be mixing (scrap card, usually) and draw two adjacent, identical circles. Fill each one, and there you go.