The heat sink may be a bit overrated, but we had such thing laying around. My DH machined three grooves on the heat sink where we glued strips of circuit board, for soldering the LEDs. I made very simple layout for the copper strips on the computer and printed on transparency film, which was transferred to the circuit board treated with UV sensitive coating with the UV light. We went maybe a bit overboard when building the prototype, but since these LEDs are just mounted by soldering the legs, we got them on the heat sink by using the circuit boards strips embedded in the grooves.
I do not have to ask my DH about the current limiting, since I calculated the resistor value. The LEDs are rated for max 400 mA, but we are limiting them now to 300 mA, with a 64 Ω power resistor. The power supply is an old 19.5 VDC laptop power supply which is rated at 4.7 A.
My DH planned to build a driver, but this is now a prototype for testing, so we needed quickly make something to power it up. My DH is experienced with power electronics, so he'll do the more demanding stuff. We have the same degree, but I have been doing mainly software and product engineering, so with electronics I'm only good when it is about applying the Ohm's law.
Sari