Here in SD we have a legal device called a warehousmen's lien. Takes very little to get it put on an item. Unfortunately, had to use it a few times. Some customers seem to think a shop should offer unlimited free storage for their projects...... Paperwork is the same as a mechanic's lien, just has to do with the storage part instead of the parts and labor of a job. Most of the time, the customer realizes your serious and gets his stuff out of the way....