My shroud came with the rad, but with fans fitted it was VERY close to the water pump. I ended up reversing it to give enough clearance, sits about 10mm from the rad fins. It's just alum sheet with a 10mm fold on all sides, the vertical sides have an extra fold to allow it to attach to the rad.
Benny's idea would be virtually the same, use some flat sheet with angle attached. Also, you could get a piece of flat sheet bent up at a sheetmetal business.
The rads are great for the money, I ran my car on the freeway and through heavy traffic in 36deg heat for two days in a row with no fans and the temp didn't go any more than two-three needle widths above half. I managed to undo the power wires without realising it