It is simple logic that you have to be invited, before you actually come and participate. So, [wərkˌsh äp] is planning to provide all potential visitors with special invitations!
They should embody the idea of interaction and touch the senses, so, here are some ideas concerning the form of these invitations.
1) ruler ( which is great in terms of presenting the [wərkˌsh äp] as the place, where the design professionals are working using all the iconic tools)