Fallout 3

For this, you have to create one of each of the custom weapons on a workbench.

The weapons are; Shishkebab, Bottlecap Mine, Dart Gun, Nuka-Grenade, Railway Rifle, Rock-it Launcher and Deathclaw Gauntlet.

Here is a list of the ingredients needed and the location to find the plans;
[Note that there is a perk in the DLC called Warmonger, which is available at level 26, which awards the plans, without having to go on an extensive treasure hunt.]

Shishkebab;
[Motorcycle Gas Tank & Handbrake, Lawnmower Blade, Pilot Light]
-Sold by Lucky Harith
-Brotherhood Outcast Shack,
-Blood Ties. Possible reward

Dart Gun;
[Paint Gun, Radscorpion Poison Gland, Toy Car, Surgical Tubing]
-Head of State. Possible reward
-MDPL-05 Power Station, near skeleton
-Tenpenny Tower, Sold by Lydia Montenegro

Bottlecap Mine;
[Lunchbox, Cherry Bomb, Sensor Module, 10 Bottle Caps]
-Tenpenny Tower, Inside Dashwood's Safe
-The Wasteland Survival Guide, awarded by Moira Brown.
-Little Lamplight, Sold by Knick Knock
-Jocko's Pop & Gas Stop

Rock-It Launcher;
[Vacuum Cleaner, Leaf Blower, Firehose Nozzle, Conductor]
-Trouble on the Homefront. Behind your
mother's favorite Bible verse plaque [Average] in your fathers lab.
- Craterside Supplies, sold by Moira Brown
-Sold by Crazy Wolfgang
--In the bridge tower third-floor armory [Very Hard]

Nuka Grenade;
[Nuka-Cola Quantum, Tin can, Turpentine, Abraxo Cleaner]
-Hidden inside the Yoo Guai Cave, at cliffside caverns
-Sold by Doc Hoff
-The Nuka-Cola Challenge. Possible reward

Deathclaw Gauntlet;
[Wonder Glue, Leather Belt, Medical Brace, Deathclaw Hand]
-Minor Quest, Council Seat. Possible reward
-On body of Wastelander beside deathclaw
-F. Scott Key Trail & Campground

Railway Rifle;
[Fission Battery, Pressure Cooker, Steam Gauge Assembly, Crutch]
-Stealing Independance. Possible reward
-Underworld Outfitters, sold by Tulip
-MDPL-13 Power Station

If you are having trouble locating the materiaals, you could use http://fallout.wikia.com/wiki/Fallout_3_component_locations as an aid.

Bottlecap Mine

Schematics Locations:
- A quest reward from Moira in Megaton after the Minefield portion of the Wasteland Survival Guide quest.
- Jocko's Pop & Gas Stop, northwest of Tenpenny Tower and east of Girdershade.
- Dashwood's safe, in Tenpenny Tower, received for completing A Manhandled Manservant.
- One can be bought from Knick Knack in Little Lamplight.

Components and Locations:
- 10 Bottle Caps
- Cherry Bomb- Pinkerton's Lab
- Lunchbox- Super-Duper Mart
- Sensor Module- Super-Duper Mart

Dart Gun

Schematics Locations:
- A schematic can be obtained from Hannibal Hamlin for completing the Head of State quest for the slaves.
- A schematic is at the Boutique Le Chic in Tenpenny Tower and if the player sides with ghouls during the Tenpenny Tower (quest), it can be purchased twice: once from Lydia Montenegro and again from Michael Masters, the ghoul who takes over.
- A schematic can be found at the MDPL-05 Power Station next to the skeleton of a dead engineer.

Components and Locations:
- Paint Gun- Super-Duper Mart
- Rad Scorpion Poison Gland- Kill a Radscorpion
- Surgical Tubing- Super-Duper Mart
- Toy Car- Super-Duper Mart

Deathclaw Gauntlet

Schematics Locations:
- Probably the easiest way to obtain the weapon schematic is at the F.Scott Key Trail & Campground. The schematics are located in a trailer usually guarded by a Deathclaw. (Killing the Deathclaw should net one of the items necessary to create the Gauntlet.)
- Another schematic is rewarded for completing the Council Seat quest in favor of Bannon in Rivet City.
- The third schematic is found on a Wastelander Settler in the "Wounded Deathclaw" random encounter.

Components and Locations:
- Deathclaw Hand- Old Olney
- Leather Belt- Super-Duper Mart
- Medical Brace- Super-Duper Mart
- Wonderglue- Super-Duper Mart

Nuka Grenade

Schematics Locations:
- Nuka Grenade schematics can be found in Cliffside Cavern. Go through the caverns to access the Yao Guai Cave. The schematics are on the "ground" floor at the northwest-most part of the cave, among a pile of skeletons.
- If you complete The Nuka-Cola Challenge, you can obtain schematics for this weapon.
- The Caravan Merchant Doc Hoff sells the Nuka Grenade schematics.

Components and Locations:
- Abraxo Cleaner- Super-Duper Mart
- Nuka-Cola Quantum- Super-Duper Mart
- Tin Can- Super-Duper Mart
- Turpentine- Super-Duper Mart

Railway Rifle

Schematics Locations:
- Can be bought from Tulip in Underworld.
- Inside the Power Substation (on the workbench) of MDPL-13 Power Station.
- Reward for Stealing Independence for Abraham Washington.

Components and Locations:
- Crutch- Pinkerton's Lab
- Fission Battery- Pinkerton's Lab
- Pressure Cooker- Super-Duper Mart
- Steam Gauge Assembly- Super-Duper Mart

Rock-It Launcher

Schematics Locations:
- Can be bought off Moira Brown in Megaton for a price of 799–1200 bottlecaps (depending on Barter skill level).
- In the armory of Rivet City, located in the ship's bridge tower.
- Can also be bought (or stolen via pickpocketing) from the traveling merchant Crazy Wolfgang.
- Another copy of the schematics can be found in the "Framed Quote" within the Vault 101 clinic.

Components and Locations:
- Conducter- Craterside Supply
- Firehose Nozzle- Craterside Supply
- Leaf Blower- Craterside Supply
- Vacuum Cleaner- Craterside Supply

Shishkebab

Schematics Locations:
- One set of schematics can be obtained from Vance at the end of the Blood Ties questline.
- Lucky Harith, the weapon specialized Caravan Merchant, sells a set of schematics.
- You can find a set near a workbench in a red Brotherhood Outcast shack, to the south-west of SatCom Array NN-03d. The shack does not appear on the map, but is at the base of the hill the Array is built on.

Components and Locations:
- Lawnmower Blade- Pinkerton's Lab
- Motorcycle Handbrake- Pinkerton's Lab
- Motorcycle Gas Tank- Pinkerton's Lab
- Pilot Light- Pinkerton's Lab

All the items you need for the weapons can be obtained in 3 places. I suggest you make a checklist of items you need.

Start at Lucky's (south of Tenpenny Tower). Most of the items you need can be found here. However, they need to be stolen. This results in little karma loss.

After that you should visit Horace Pinkerton's Lab in The Broken Bow of Rivet City. His lab has almost every other item you need and didn't get at Lucky's (the Paint Gun is hidden in a metal box in Pinkerton's Lab).

At this time you should have everything except the Steam Gauge Assembly. This part is found in the Super-Duper Mart Pharmacy.

For the achievement you need to build one of each custom weapon. To do this you need schematics for each weapon, the items required to build each weapon and a work bench to put it all together. The fastest way to pick up each schematic are listed below. Workbenches can be found all over the wasteland, an easy location is the workbench in rivet city near Flank and Shrapnel's weapon shop.

Bottlecap Mine:
* Jacko’s Pop & Gas Stop: On the work bench, inside the shop.
* Little Lamplight: Sold by Knick Knack.

Dart Gun:
* MDPL-05 Powerstation: Inside the fence on the ground near the skeleton.
* Tenpenny Tower: Sold by Lydia Mantenegro.

Deathclaw Gauntlet:
* F. Scott Key Trail & Campground: In the caravan, in the picnic area.

Nuka Grenade:
* Cliffside Caverns: Located in the very back of the caverns near a large rock and a bunch of skeletons

Railway Rifle:
* MDPL-13 Powerstation: Located inside the main building on the workbench.

Rock-It Launcher:
* Megaton: Sold by Moira in Craterside Supplies.

Shishkebob:
* Brotherhood Outcast Shack: On the table located near the workbench.

All items needed to build the weapons can be found by scouring the wasteland. Here are a few items I had a hard time finding.

* Crutch: There is a sniper located north of the Minefield where Moira sends you during the Wasteland Survival Guide Quest. On the top floor of the building he snipes from is a mattress, and located behind that mattress in the corner is a crutch.

* Pressure Cooker: Fort Constantine, located in the CO's Quarters. It's on the stove in the kitchen.

* Firehose Nozzle: Germantown Police HQ, Located inside the red boxes throughout the halls. They are also located in all public buildings.

There is a perk which gives you all the schematic's, tier 3.
if you don't know when you get a second or third copy of a schamatic it makes the item better, bonus damage, defense, extra effects, etc
these are called tier's

How i got this achievement easy was
after getting your house save one of everything you find,
examples, lunch box, abraxo cleaner, tin can, leather belt.
This way you can save before you get this perk,
and then unlock the perk go to your house make everything you can, and then go around to every trader your aware of and buy what you don't have.
Afterwards reload your old save and chose a better perk.
oh and if your still missing something check falloutwiki just type in what your missing and it will give you good place to search for it

if you wish to leave negative feedback please also leave a comment stating how i can improve this guide