Most Warframe blueprints can be purchased from the Market for Credits. When purchased this way, the Tenno will need to acquire the Chassis, Neuroptics, Systems from Assassination missions and a number of Orokin Cells to craft the frame in the Foundry. Prime Warframe blueprints are obtained as drops from various Void Relic missions and cannot be bought in the Market.
Once a Tenno has the blueprint and all required components, they can begin crafting the Warframe. The crafting takes 72 hours and costs thousands of credits. Crafting can be rushed to instantly finish the Warframe for 
50. Tenno crafting a new Warframe will need to have an available inventory slot to claim the new Warframe, which can be purchased for 20.
Alternate Helmets
Most Warframes have alternate helmets that can be acquired to change their appearance and in some cases modify their stats. The Helmets can be purchased from the market for 75 or the blueprints can be obtained through Alert Missions. Developers at Digital Extremes have stated that alternate helmets acquired now will not have statistic changes attached to them; however, existing helmets with statistic changes will remain as Arcane Helmets with this change in policy.
The helmet cannot be sold or lost.
Prime Warframe Blueprints
There are currently twelve Prime Warframes that have been released that can be built with a blueprint: Ash Prime, Ember Prime, Frost Prime, Loki Prime, Mag Prime, Nova Prime, Nyx Prime, Rhino Prime, Trinity Prime, Saryn Prime, Vauban Prime, and Volt Prime.