Velcro stickers and rubber feet from the 1-Euro store, and the handle of an old toilet plunger.
I had to flatten the plunger handle on one side to make more of the velcro stickers connect.
With tenting I really would like to have more aggressive staggering for the pinky column though.
Update: the velcro tape is also really good for sticking them to smartphone holders.
Where would I find these smartphone holders
I bought them from bol.com in EU, but they are also available from Amazon.