We get this question alot. Every once in a while I do hear about our customers handling the assembly.
A few tips:
1.) Put small ticks in the print that help your customers align the stands to the middle of the
sign
2.) Stack the
signs upside down against a wall and do them all at once. This helps you determine the placement of the frame using the last
sign you just did.
3.) Many
sign shops we work with will handle the assembly if their customer is only ordering a few
signs (1-5). This is a bit of a value added service and is worth the effort in my opinion.
To answer your question though, doing 250 of them should probably require some kind of charge for the labor involved. One reason to tell customers not to assemble before they're ready to be used is storage.
Signs and stands sit nicely in boxes on their own, but after assembly they seem to take up 5 times as much space, they are somewhat unsafe and they risk getting scratched in handling.
Good luck!