Aside from poking around the miscellaneous tubing fittings and couplings in the plumbing area, go to the garden section of your home center and look at the valves and fittings used for drip irrigation. Those are designed to let you regulate the flow on a 1/4" tubing system.
Following is a link to a series of pictures of my lapidary bench. My trim saw is the only real drip system. The slab saw uses a sump that the saw turns through. My grinding sanding and polishing bench is served by a system made from fittings found at the local plumbing store for probably less than $100. It includes a large plastic tub or sump to hold the coolant. Inside the tub is a smaller plastic bucket into which I have installed a small pool sump pump. The pump delivers coolant to each of three ball valves that can adjust the flow of coolant to my expansion wheel lathe, horizontal lap and diamond grinding and resin wheel lathe. The larger drain system collects the coolant and brings it back by gravity to the sump. Note that the pump is in a bucket so that clean water flows from the top of the sump to the pump. The dirty coolant is delivered to the bottom of the sump so that dirt can settle out into the sump and not just get recirculated (kind of like a septic tank). Each device is driven by a separate motor as is the pump. They all have their own on/off switch. This system works very well and assures that relatively clean coolant is delivered to all locations…Rob