To make a new warframe you need a chassis, head, systems, and then you need to purchase blueprints and find all of the materials. All planets say which materials they provide, but they don't say if you can find any warframe parts there.
Where can I get the parts for every warframe?
Bosses at the end of each planet. Here's the current list:
http://guidescroll.com/2013/01/warframe-boss-locations-and-drops-list/
Boss: Captain Vor
Planet: Mercury
Level: Tolstoj
Faction: Grineer
Drops: Cronus longsword/Seer Pistol Blueprint Parts
Boss: The Jackal
Planet: Venus
Level: Fossa
Faction: Corpus
Drops: Rhino Warframe Bluprint Parts
Boss: Counceler Van Dek
Planet: Earth
Level: Everest
Faction: Grineer
Drops: Trinity Warframe Bluprint Parts
Boss: Sargent Nef Anyo
Planet: Mars
Level: War
Faction: Grineer
Drop: Mag Warframe Bluprint Parts
.
Boss: The Golem
Planet: Jupiter
Level: Themisto
Faction: Infected
Drops: Volt Warframe Bluprint Parts
Boss: General Sargas Ruk
Planet: Saturn
Level: Thetys
Faction: Grineer
Drop: Ember Warframe Bluprint Parts
Boss: Tyl Regar
Planet: Uranus
Level: Titania
Faction: Grineer
Drop: Ash Warframe Bluprint Parts
Boss: The Hyena
Planet: Neptune
Level: Psamathe
Faction: Corpus
Drops: Loki Warframe Bluprint Parts
Boss: Ambulas
Planet: Pluto
Level: Hades
Faction: Corpus
Drop: Excalibur Warframe Bluprint Parts
.
Boss: Lt. Lech Krill
Planet: Ceres
Level: Exta
Faction: Grineer
Drop: Frost Warframe Bluprint Parts
Boss: Phorid
Planet: Eris
Level: Naeglar
Faction: Infestation
Drop: Nyx Warframe Bluprint Parts
Boss: Kela De Thaym
Planet: Sedna
Level: Merrow
Faction: Grineer
Drop: Saryn Warframe Bluprint Parts
Boss: N/A – Given as Reward at the end of each mission
Planet: Europa
Level: Intel, Captured and Defense Missions
Faction: Infested/Corpus
Drop: Banshee Warframe Blueprint Parts
Boss: Alad V
Planet: Jupiter
Level: Themisto
Faction: Corpus
Drop: Valkyr Warframe Blueprint Parts
Alerts:
+ Dark Sword, Plasma Sword, Jaw Sword, Pangolin Sword, Heat Sword,
+ Heat Dagger, Ceramic Dagger, Dark Dagger, Glave
+ Orikin Catalyst and Reactor
+ Alternative Helmets
+ Orikin Artifact Cards
The best practice if you want to build a Warframe is to go to this Warframe Wikia page and choose which Warframe you want to build.
Then inside every Warframe detail page, you can find who/where you can drop the items needed.
For example in the Ember page it says
Component blueprints drop from General Sargas Ruk (Tethys, Saturn)
I always suggest to visit the wiki because it happened that after an update, all the components for a specific Warframe were dropped by a different boss, or even not dropped at all anymore! The wiki usually mantains those informations as updated as possible.
Also, not every Warframe is dropped by a boss. For example the Vauban components can only be found in Alerts, Mirage components are found during a specific Quest, while Banshee components can be bought inside a Clan Dojo.
The list above was good, but with recent updates, it got changed. There are more Warframes and new locations.
Boss Drops - Each one must be killed 3+ times to get each part.
---Rhino - Jackal (Fossa(Venus))
---Oberon - Vay Hek (Everest(Earth))
---Valkyr - Alad V. (Themisto(Jupiter))
---Mag - Nef Anyo (War(Mars))
---Ember - Sargus Ruk (Tethys(Saturn))
---Trinity - Lech Kril + Vor (Iliad(Phobos))
---Ash - Tyl Regor (Titania(Uranus))
---Loki - Hyena Pack (Psamathe(Neptune))
---Frost - Lech Kril (Exta(Ceres))
---Excalibur - Ambulas (Hades(Pluto))
(http://warframe.wikia.com/wiki/Planets)
Research Drops - These must be researched in the clan dojo.
---Zephyr - Tenno Research
---Banshee - Tenno Research
---Volt - Tenno Research
(http://warframe.wikia.com/wiki/Research)
Prime Drops - These are earned from the Orikoin Void and Derelict Missions. The locations sometimes change, so I would advise looking at the Wiki to double check the locations.
---Ember Prime ---Frost Prime ---Mag Prime ---Rhino Prime ---Loki Prime
(http://warframe.wikia.com/wiki/Orokin_Void , http://warframe.wikia.com/wiki/Orokin_Derelict)
Random Boss - The only random boss Warframe is Nyx, who drops from Phorid manifestation. A Phorid manifestation appears when an Infestation outbreak reaches a boss fight.
Alert - The only alert warframe is Vauabon. He is extremely hard to get seeing that there is a very low chance that when an alert appears, it will be a part. And, if it is, there is always the chance of it being one you already have.
Quest - Purchase and build the quest from the market and complete it to get parts of Mirage and Limbo.
It is true about all of the Warframe drops above except for Ash. They took out the Ash blueprint part from Tyl Regor on Titania. Now, instead you get equinox parts. The new way to get Ash part is to kill Manics. Kinda like Oberon, they will drop in missions as glowing objects. Manics are fast and hard to hit, but too deadly to ignore.
You need the blueprints to manufacture those parts; those blueprints are usually dropped by named mobs in the game, the targets of assassination.
Example - The Ash Chassis, Helmet and Systems blueprints are all dropped by Tyl Regor, on Titania in the Uranus System.
