Below is a walkthrough for the Working Blueprint side quest in Tiny Tina’s Wonderlands. To obtain this quest, speak with Borpo near the Shattergrave Barrow map transition in Overworld after starting the Thy Bard, with a Vengeance main quest.
Go to cave
Travel to the cave east of the Shrine of Mooh Al and deal with the random encounters. There will be 2 total. Loot the blueprint from the chest that spawns after the second encounter completes.
Talk to Borpo
Return to Borpo and speak with him to complete the quest.