Drops you can get in any difficulty, as mentioned. The initial "Plans" to train the blacksmith drop of izual, boss before Diablo (If I remember correctly, you have to get them as a drop the first time)
Black Mushroom – Found in Level 1 of the Cathedral in Act I
Start a new game at Act I, Quest 3: A Shattered Crown.
Take the waypoint to the Cathedral Garden, then enter Leoric’s Passage.
Head up the stairs to Level 1 of the Cathedral and search every room until you find Black Mushrooms.
Leoric’s Shinbone – Found in Leoric’s Manor in Act I
Start a new game at Act I, Quest 9: The Imprisoned Angel – Part 2: The Cursed Hold.
Take the waypoint to Leoric’s Manor.
Enter Leoric’s Manor – go up the stairs, down the stairs, then enter the first room on the left and look for Burnt Logs in the fireplace at the far wall.
If there are no burnt logs, then exit and retry. If the burnt logs are there, then click on them and loot Leoric’s Shinbone.
Wirt’s Bell – Sold by a vendor in Act II
Little girl in the Bazaar
Liquid Rainbow – Found in the Mysterious Cave in Act II
Start a new game at Act II, Quest 6: Betrayer of the Horadrim – Part 2: The Forgotten Ruins
Take the waypoint to Path to the Oasis.
Head east – keeping to the south – and look for the first path that leads to a small hut where Zaven the Alchemist is being attacked by some Deathly Haunts. If Zaven is not there – exit out and retry.
If the event is happening…kill the phantoms and then Zaven will talk to you. He then opens an entrance to the Mysterious Cave.
Enter the Mysterious Cave and look for the Mysterious Chest. Open the chest and loot the Liquid Rainbow.
Gibbering Gemstone – Found in the Caverns of Frost in Act III
Start a new game at Act III, Quest 6: Siegebreaker.
Take the waypoint to Korsikk Bridge.
Head east into the Fields of Slaughter and look for the Caverns of Frost. If you see Icefall Caves, exit out and retry.
If the Caverns of Frost event is spawned, enter the cave, head down to level 2 and look for Chiltara. If Chiltara is not spawned, then exit out and retry.
If you get lucky and find Chiltara, then kill her and take her gemstone.
Plan: Staff of Herding – is a random drop off of Izual in Act IV
Start a new game at Act IV, Quest 4: Prime Evil.
Take the waypoint to the Crystal Colonnade.
Enter the Gateway to the Silver Spire and make your way to the Great Span.
Kill Izual and loot the plan. If he doesn’t drop it, then exit out and retry as needed.
Rt click the "Plans" at the blacksmith to train.. then do the combine (under weapons/staves). The initial staff is normal mode only, regardless of what diff you got the "parts" from. Once you have the staff created, you can purchase upgrade plans from the quartermaster (merchant near the mercenaries) in the keep (act 4) on each new difficulty.
The new plans, rt click train just like the first one, and the recipie is the last tier staff + Money. Because of this, you have to upgrade them in order,
Initial Combine - parts above + 50k = staff of herding
Nightmare = Normal Staff + 200k + plans from QM in Nightmare mode
Hell = Nightmare Staff + 500k + Plans from QM in Hell Mode
Inferno = Hell staff + 1m + Plans from QM in Inferno.