Do think about the shape and position of the portholes. Different parts of the building process become interesting at different times and the portholes should be positioned in order to maximise viewing opportunities of all the different stages of the process
 
Do make sure that the portholes are low enough for children to see into the site
 
Do make sure that there is either a metal grill or a Perspex sheet covering the portholes - people should be able to see in easily, but not fall or climb in
 
Do think about working with a local artist or designer to create original and eye-catching port-hole shapes, perhaps reflecting the nature of the building or the town it is in

Don't forget safety aspects of the process - the local authority will be able to advise on these
 
Don't forget to be bold - port-holes can be excellent local landmarks and create press opportunities to publicise your work and the future purpose of the building