I bought a kitchen digital scale at Wal-Mart, weighs to 5+ pounds ±1/8 oz or ±2 gr, 9V battery. Has a platform or a tray. Zeros for tare on turn on, or with push of zero button. About $30. Can be used for mixing epoxy but a platform beam balance (OHAUS) is better for that.
I also got a ROYAL ds5 digital at Sam's club or maybe COSTCO, about $20, accurate to ±1 gr, ±.1 oz.. 9 Volt It has a convenient "hold" feature that makes it easier to read, and "tare". And BTW has all the postal rates on a chart on the platform.