A friend suggested the 41 x 41 x 2mm Unistrut mounted upside down, ie with the opening at the top, would be an ideal track then you can use four or six of the 4 wheel roller assemblies attached to the roof in the tracks.
I think I'm going to go this way and I'm wondering if anyone else has done this ?
My roof will be 3 mtrs long and 2.2 mtrs wide and fairly light, possibly dark coloured plastic roof sheets.
The whole obsy is being made from patio tube, 76 x 36 I think it is, with steel sheet cladding, all sourced for free from my local radio club
Cheers