As is you need me on your trips
Left alone you use me on your trips
Rearranged some use me on their trips
Short and thin
I carry a pin
Who am I?
It could be
VISA
As,
VISA is needed to make trips.
Rearranged, visa can become AVIS, which is plural of AVI- which is a kind of self-proclaimed identifying means- which is again, needed for making trips.
Though,
VISA ( or its representation in the form of a small stamp) is small, it's issuing authority is generally big( a country).
And finally
you can have a pin on your visa card to get a cash advance and AVIS is a car rental company- Thanks to SteveV
Is it:
A credit/debit card?
As is you need me on your trips
You need them to pay for the trips
Left alone you use me on your trips
You used them to cvoer expenses on your trip
Rearranged some use me on their trips
Not sure
Short and thin
The plastic is small and thin
I carry a pin
The PIN for the card is stored on it.
I believe it's a:
Briefcase?
As is you need me on your trips
You need them to store your belongings on your trips.
Left alone you use me on your trips
It's always in use, keeping your stuff together.
Rearranged some use me on their trips
Not all people are organised, but some tend to organize their briefcases.
Short and thin
Quite arguably so.
I carry a pin
Briefcases tend to have a 3 digit PIN.
And as to "I may be small but my maker is big and powerful":
Briefcases are manufactured in big factories by big brands.
I believe it's a:
backpack, all fits and goes on trips