My FPV kit arrived about a week ago, having opted to get the (relatively) humongous 2W transmitter (at 180g) and which does not have any mounting to speak of.. what you get is an aluminum heat sink and perforated steel sheet casing at the bottom.

Some folks insert steel clamps at the bottom, whatever those are they must really be small and almost impossible to find anywhere.  My solution was make a custom mounting made out of PVC sheet using good ‘ol used phone cards (or credit cards).  The first thing to that needs to be done is to take the screws off the the fan (dont worry they’re pretty much securely screwed in the aluminum heat sink):

The next step is to cut out some kind of base from the phone card, this will be attached and screwed on top of the fan.  Dont worry the screws are long enough for a good secure fit.  Here’s the end result:

Now this transmitter is ready to be mounted anywhere!