Thinking about it yes 4 axis will probably mean a lot larger machine as each side would need to have two indipendant axis so that may be out for the moment two axis cnc would still be nice. What I was thinking was if it was a gantry type build then I build each side with two rails a horizontal and vertical and then ether drive the with desperate motors or connect them via a shaft and pulleys. The horizontal cut is the most important but I would probably use a open loop belt to drive all axis