The micro-miniaturized feat says that whenever I build or request a gadget, I may include one additional mechanism per gadget. Does this mean I get an additional gadget pick, or that I may simply expend another gadget pick to put more mechanisms in a housing than what is usually possible?
The Feat Doesn't Provide Free Stuff
The Benefit of the feat Micro-miniaturized (Spycraft 2.0 197) says
When you build or request a gadget, each Mechanism is 1 size category smaller, and you may include 1 additional Mechanism per gadget.
No mention is made of how to include the additional Mechanism therefore standard rules apply. The feat Micro-miniaturized merely allows an additional Mechanism in a housing--it doesn't provide a free Mechanism. The additional Mechanism must still be built or requested,1 its cost paid normally.
That is, gained when mission or personal gear can be selected, not only upon making a successful Request Check:
[The game] generally use[s] the term "request" to mean "acquire" through any means other than picking it up in game, so the feat [Mirco-miniaturized] covers possessions and mission gear as well.