Features have a field "metal_value", but empirically, reclaiming them returns 2 ticks at the fabber's rate, reguardless of the listed metal value. (So not only do combat fabs save on energy, they get a lot more metal) Is the data field a relic of code past?
I've had a couple of breakthroughs. 1. I have to shadow all the individual features (with no changes) in order to changes in their base templates to be used. 2. I can set reclaim value, it's just... odd. You can get (metal_value/max_health)/10, plus some error based on the build power used (I've discovered that econ errors are everywhere, but nobody notices in a streaming economy) In the typical case, a feature is either 25/25/10 or 25/10/10 for trees, basically 1 metal if you round up generously, and the fabber error dominates. Edit: forgot the /10
Same thing happens when you repair or build too. You always pay or reclaim extra metal based on build power.