Customers sometimes have to travel for some hours - at least where I live, just to have an open glue joint between the rib and the table (or back) glued. Gluing takes just a few minutes, but drying takes hours. To save customers (and the environment) a second trip, I've made some clamps that can be used for this job.

If I have reason to believe that the customer is not the clumsy type, and that the instrument is of a rather common type, I can send him home with the clamp(s) on the instrument, inside his case, and the "key" necessary to take it off. Plus an envelope with which he can return the clamp.

It's advisable to loosen at least the two middle strings in case the string tension influence the alignment of the rib/table.