I think Braza's problem may be one that Archicad can't solve directly?
Let me explain what I think the problem is, and if I am wrong please correct me.
The beams come in standard lengths of 6m & 12m and can be cut to any size.
Braza need in his job one beam 3m long and another 8m long.
Expressions in properties could be used and will determine that for the 3m beam he must order a 6m beam and for the 8m beam he must order a 12m beam.
In fact he only needs to order one 12m beam as he can cut both the 3m & 8m beams from it.
I don't think there is a way for Archicad to determine that the waste from one cut can be used for another shorter beam.
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