Sounds like you don't need much speed for that task, so perhaps 12V supply will be fine.The A3967's however are an issue with a 1.7A motors, since it can only handle an absolutemax of 0.7A or so and thus won't hack it at all.DRV8825 is a better choice for higher current, probably set to 1.5A they would hold upfor that motor.If you do the I-squared-R calculation for the motors you'll see each will dissipate around 4.5W,so 9 in total at 1.7A (perhaps more like 7W if programmed at 1.5A). Allow for losses in thedriver and the need to provide mechanical power as well as just heat the windings (!),perhaps about 15 to 20W input power, so 1.25 to 1.8A at 12V (or about half that for 24Vsupply). It you do need high speed, 24V is better. I'd therefore say 1.5 or 2A supply at 12V ora 1.0 to 1.5A supply at 24V.Rating supplies generously is a good thing, they run cooler and last longer, so don't be shy to go for a somewhat higher current rating if the cost isn't dramatically different.