Yakuza 3

All the weapons and items you've been finding/collecting will finally come to use. The weapon store (not van) in Ryukya (next to the Ryudo Family Offices) finally allows you to do something with all that weird shit you couldn't find use for. Buy or find DVDs so you can learn how to put together new weapons with found materials.

NOTE: You don't have to be carrying the specified items to make a modded weapon. For example: If you wanna make a "Shixt Shooter" (TM, me) and you need a Shotgun, a piece of horse shit, and a clothes hangar, you don't need those items equipped. When making a modded weapon, you can access your hideout's inventory. Keep that in mind.