There is a method of mixing small batches of epoxy accurately without the use of scales. Use the syringes designed for administering medicines orally to children. These are available, sometimes for free from your pharmacist, in 5cc and 10cc sizes. Some brands even come with a cap, although some pharmacists discard the caps in fear that children will ingest them. These syringes are very accurate, and very little epoxy is wasted in their use.

Mark one syringe for resin, and one for hardener. Store them in plastic baggies between uses to keep them clean. Additionally, they can be cleaned, occassionally, with hot, soapy water. I also clean the syringes prior to their first usage, just in case there is some kind of lubricant on the rubber piston.

The obvious question is: "How can I suck the resin or epoxy out of a part-full gallon or quart container with a tiny syringe?" Easy. Decant/store some resin and epoxy in wide-mouth jars.