Slots in Copper Bolster

[hearthammer]

I am fairly new to knife making and on a tight budget (4 kids take priority over my interests). For now, I am using the stock removal method. Eventually, I plan on going into forging. I have 2 irons in the fire so to speak. One is a Smallish tanto carved from a mill bastard. The other is a much larger fixed blade fighter/survival knife also a mill bastard. Not having a mill, lathe or surface grinder at my disposal, I have been filing the blades by hand using a band file.
My question is this; are there any tips or tricks on slotting a bolster or habaki without drilling holes and filing them out? The bolster material is copper.