A number of different types of traps can be created, and include spike, acid, gas, fire, holy, negative energy, frost and electrical. The destructive level of each trap is determined only by the number of reagents put into the bench.
The four levels of traps and the Craft trap skill required to make them are:
Craft Trap 5
Craft Trap 10
Craft Trap 15
Craft Trap 20
The crafting of traps is fairly straightforward. Simply take a trap mold and place it into the blacksmith's bench along with the appropriate reagents. Use the smith's hammer on the bench and the trap is made.
Reagents used in trap making include: acid flasks, alchemist's fire, choking powder, coldstones, daggers, holywater, obsidian, quartz crystal, tanglefoot bags, and thunderstones.
They can be purchased from various merchants, trap molds are more limited in supply. Recipes for traps can be found in various tomes in the game.
Tip: Uncus at Crossroads Keep usually has a large supply of both trap molds and reagants available.