Is their any reason to keep blueprints to stuff I already have?

[juujii]

Is their any reason to keep blueprints to stuff I already have? For example, I have tons of blueprints to warframes and weapons I already have. Should I just sell them for credits/clear up space in my foundry?

[Cyborg-Rox]

Yes, in case you'll need the weapon to build something else later, or if you at some point end up selling the weapon to spare a slot.

[Aurea_Hiigara]

It depends a bit on the blueprint, mind you.

Blueprints for Prime weapons and warframes can be traded to other players for platinum, while the more common stuff (like Nyx and Oberon pieces, Gorgon Blueprints etc.) aren't tradable and just an extra source of credits.

[WrathAscending]

I generally try to keep one of everything as a crafting component for other things even if I've already used and mastered things. That way when Tenno Reinforcements drop you can get to work on the new weapon immediately.

There's also no way to predict when certain weapons will be removed from circulation. For a while the Gorgon was all-but unobtainable since the blueprint and weapon were removed from the market and it was available only as a log-in reward. The Boar meanwhile could only be obtained as part of the Wrecking Rhino pack with no other way to get one. The Snipetron and Machete are presently gone completely too.

[Daiwulf]

Some weapons/frames are also building material for other weapons/frames (akimbo secondaries (need 2x weapons), nikana->dragon nikana, chroma parts, for example). So you might save 1 extra BP for the ones like nikana (if you want to also keep the material weapon), 1 for chroma (need other warframe parts to build chroma parts) and 1 for akimbo weapons (2 if you want to also keep the solo weapon).

For Primes, duplicates can be sold to other players for platinum, or exchanged at relays for ducats. Also, some prime parts are needed for syndicate advancement(last level for new loka and red veil require neuroptics from vauban and ash, for example). Also, there is Akbronco Prime that needs 2 Bronco Prime, so keep an extra BroncoP Set for that one. 

Other than that, sell them for credits.

Edit: Note that you only need to level up a weapon to 30 once for mastery, so if you get a duplicate to build another weapon, use the level 0 weapon in the recipe so you don't waste time using your leveled item and then leveling the other one again for no mastery.

Edited December 18, 2016 by Daiwulf

[(XBOX)ThermalStone]

If you haven't built Chroma, there are some non prime warframe BPs you'll want to keep.  Look him up.  otherwise sell all your non prime warframe blueprints.