Attaching the flags:
On the Rietveld building I could use magnets to attach the flags (due to the aluminium coating on the Crouwel building I had to find an alternative).
6 people mounted the flags within a day.
Thanks to the sewn-in block magnets Q-20-04-03-N
(5 per flag) the flags could easily be attached to the Rietveld building.
The magnets were strong enough to hold up the flags for 9 days, even during bad weather.