sory i post here and in law forum, because i think there are similar laws in many countries:
in france law is very clear:
some compounds are illegal, you can go to jail for only having some.
but designer drugs are not really legal because you cannot sell or give a product which have similar properties as illegal compounds (hallucinogenic, stimulant, and/or relaxant), you can go to jail for giving or selling even non-active compounds, saying that they are active...
so: you can go to jail too for selling ephedrine in low quantities because it is stimulant whereas in france you can buy some pseudoeph at the pharmstore without medical order (non listed medication)
for the ephedrine: selling it in the caps saying that it comes from the pharmstore you can go to jail for 2years whereas selling it in powder, in same quantities you can go to jail for 10 years (in the 1st case you risk because you sell medication without being pharmacist, in the second case you risk because you sell compound which has similar properties as illegal drugs)
finally in France you wont risk anything producting and consuming ALone things like methphentermine, but if someone says you have sold or given him some, you can go to jail for 10years...