Are you sick of the anxiety that comes with running out of lockpicks in Persona 5? Well, then you may want to spend some extra time working toward the Eternal Lockpick, a infiltration tool with unlimited uses.
You will not be able to access this tool until you have completed several palaces and upped your social link with Morgana. Once you have at least level six of the Magician Confidant, Advanced Infiltration tools will become available to you. However, just because you can build it doesn’t meant that you have the resources.
The Eternal Lockpick requires 20 Aluminum Sheets and 10 Liquid Mercury. It is entirely likely that you won’t even have one of the 10 Liquid Mercury needed when you begin your quest to build this thing. The regents are very rare and only drop off of a few enemies.
For the Aluminum Sheets, take down Anzu and Ganesha in Futaba's Palace and Okumura’s Spaceport respectively. For Liquid Mercury, kill Anubis in Futaba’s Palace and Decarabia in Okumura's Palace. Remember that if you hold enemies up, you can ask them for items. Keep in mind that many old enemies will appear in Mementos after you compete their palaces. Aluminum Sheet is easily gathered throughout Mementos, often appearing in the little item boxes scattered around each floor. Liquid Mercury is the real holdup here. You basically need to farm Anubis enemies on floor 10 and 11 of the Akzeriyyuth area. Keep defeating them, and eventually you will have enough for the Eternal Lockpick.
This will require a fair bit of grinding on your part to get, but think of all the time you will save if you never have to build another lockpick again.