Recruit a unit once, stake him, and he earns a share of every trade for as long as he stays at work. Need one first? Mint here.
Two one-time approvals before the first recruit: the pool needs permission to take the UNITS fee, and permission to hold the unit while he works. After that every unit is one button.
Fees collect in the pool until someone starts a payout. That call is permissionless — you, us, a stranger, a bot — and the only thing it can do is move money toward the units at work. It costs the caller gas and nothing else.