This site builds capitol equipment which seems to add a few extra wrinkles. Each of their systems has an average build cycle of eight weeks. Purchasing, sawing, machining are way downstream of the sub-assembly and assembly centers. When there are several system orders it can get overwhelming. Non-Stock is easier to track down demand/dates but requires a ton of transactions. Stock reduces the required transactions but… really complicates tracking.
Have you heard of Sigmanest?
One option would be to setup a “generic” part number and make it lot controlled. Then you could save the length in the lot number field.
For example, if the 20" length is part number 12345, you could create 12345DO, with UOM EA and Lot controlled.
Then when you have (50) 4 foot pcs, you could adjust the 12345DO part number up 50 and make the lot size 4. If another job created 6.5 foot long, then you would adjust the same part number but the lot would be 6.5.
I would recommend making a new class code as well for the drop-off part numbers. Dashboards could be created to show all of the inventory in the drop-off part class and lots could be issued to jobs
The way we do this is issue all 20 feet to the job. We have multiple UOMs set up. For example, 1 foot length, 4 foot length, 8 foot length and so on.
When they return the drops, they do a Misc Return using the UOM of the drop.
This will not relieve the job. You can also see the size of material you have, for example a 4 foot length.
It can become cumbersome when you have a lot of different sizes and odd sizes, which we do. For example, we may have a drop that is a circle cut out of a ring, or a triangle from a corner of a sheet. We usually do not inventory these or round them down to the nearest size.