Step 1: What you will need
First off, you need a location to install the heater. Preferably, if you live in the northern hemisphere, a southern exposition. The location should have as much sunlight as possible all day.
That said in terms of supply and tools , you will need:
L shape metal rods (or wood it you prefer)
2 x 64 inch 1 1/4 inch diameter copper pipes
3-4 rolls of 1/4 inch copper pipes.
Welding torch (bernzomatic, plumbers stuff)
Acetone or other cleaner that can remove soldering paste
Step 2: Making a frame to hold the pipes
Cut the rods to length to make a rectangle. on the shorter side , I made some notch with a hole saw, so the pipe will fit in. Weld the rectangle together. If you don't have a welder, or access to one. You could also drill and bolt the part together. I used some rubber to isolate the steel frame from the coper to prevent metal reactions.
Step 3: Drill the manifolds
insert the pipes onto the frame so you can evaluate where to start and stop drilling holes.
This way you will not have any holes where the manifold pipe will attache to the frame.
I have evaluated the 63 1/4 pipes will have more then 3 times the diameter of the 1 1/4 " pipe. this is to make sure the water will slow down a bit in the smaller pipes.
By slowing down the water a bit , It helps with the heat exchange...