Hi Bashy…
Fell free to make any question about this shield building. I’ll try to help you. Units in metric, sorry.
5 mm. diameter. The three main rods are 30 cm long. The small one is about 10 cm. long.
how big are the spacers, Diameter and length? (my saucers are 32cm diam x 5cm depth, spacers = 5cm or 4cm, i think 4cm?) (the 20cm saucers only have 3cm depth, that is not enough is it?
I have made the spacers from a 9 mm inner, 13 mm. outer diameter tube. Length is 21 mm. The key to make the shield work properly is what you see in pic #2. I think 3 or 3.5 cm are enough for 32 cm saucers.
Does the tube have to be aluminium or can it be a white plastic tube?
Plastic should work as well.
Whats the diameter of the fan?
The fan and solar motor is exactly the basic kit you’ve found from Maplin. It is pretty enough for this purpose. You dont need a strong current, just a tiny constant airflow. Tip: you’ll have to seal a bit the solar cell.
I take it, once completed i will be able to locate this anywhere, i.e. it don't matter if in direct sunlight?
Yes, wherever you want. Mine is working side by side with another Davis shield at full sunlight. Readings are the same.