From 35C3 Wiki
The cloakroom can store your jackets and/or luggage during the congress for a small fee.
Don't lose your receipt, we can't hand out items without it! We cannot assume liability for your stuff deposited in the cloakroom!
Where and when
somewhere, we will find out until the congress starts
We try to operate 24/7 during the congress, beginning in the afternoon on Dec 26th, closing at around 22:00 on Dec 31st.
If it is your first shift at the cloakroom, you might want to arrive 10 minutes early, so the previous shift can explain everything to you.
Lost and found
The lost and found is handled by the cloakroom team. Ask for your stuff or contact them via email firstname.lastname@example.org. In case of contact via email please be patient as they will process your request not before the end of January. The team of volunteers needs to recover from the congress, the tear down and the aftermath.
They will then sort through the boxes of found objects, prepare shipping and then start responding to email.