Thats a tall order/question.
The words "constructive intent" are thrown around quite a bit in regards to NFA items, but in reality there are very few cases that have sufaced where that was the actual charge, because it is in fact BS.
Some of us that are in the title II game just go with the flow and try and answer the questions in regards to "contructive intent" with SAFE/LEGAL responses that would not get any body in a situation to make a bad decision.
When dealing with NFA items it is best to lean on the side of caution.
Remember this, even if your intentions are clearly in the good/right, an ATF agent or a ill-informed LEO can send you on a very expensive legal roller coaster.