You can use 2200mfd 25v caps from Radi shack or others. A cheap cap dischage may be made from a trailer side light bulb between 16-18vdc and the capacitor.
The plus side of the capacitor then feeds the switch controller buttons. The common negative feeds the common terminal on the controllers.
When you push a button the cap is discharged through the switch machine and recharged quickly through the trailer light bulb. If you hold a button down the increased resistance of the lighted bulb will limit the curent and no fry the switch machine.
Atlas switch button controllers can withstand the kickback from the coils without diode protection, they are tough things. If you use small buttons you better connect diodes with reverse polarity across the switch machine coils. If the plus side of the cap discharge goes to the outer terminals of the machine and the common is negative, connec the diodes with the banded end (cathode) to the outer terminal side and the other end to the common (center) side. Larry
A lot cheaper solution than $30.00 commercial units!