The first part of the schematic for the Dart Gun are found at the MDPL-05 Power 
Station on the northwest tip of the Capital Wasteland. Another part is obtained 
from Hannibal Hamlin after completing the "Lincoln Memorial" quest for the 
slaves. The last schematic is found in a locked chest at the Boutique Le Chic in 
Tenpenny Tower. Parts required are a toy car, surgical tubing, paint gun, and 
Radscorpion poison gland. The Dart Gun cripples your target's legs. It is very 
useful when used on fast melee opponents such as Deathclaws. It also poisons 
your target for eight seconds.