First of all: I don't have the Teensy 3.2 until now, because I want to make sure that it works with my SBUS receiver.
I want to power it from the USB port. On the back side I see VUSB, but not VIN.
What kind of switch are you thinking about and where can I order it?
What do you mean with "doing the USB stuff"?
BTW: what kind of USB plug is used on the Teensy 3.2? I assume that I need a USB cable between my PC and the Teensy.
Sorry, I am a complete newbee to Arduino.
VIN is on the front side. Basically, the 28 outer pins are shown on the front side of the pinout card. The inner pins and solder pads (5 pins at the back of the Teensy, 4 internal through hole solder pins, and the solder pads) are documented on the back side of the pinout card. So if you look at the pinout card, with the USB port facing left, the VIN pin is the top left pin on the outside row, and the VUSB pin is the first inside pin, next to the AGND pin.
The Teensy 3.2 uses a micro USB-b cable to connect to the host. Make sure you have a data cable that can pass information, and not a power only cable.
For the simplest case, you would not cut the VIN <-> VUSB connection. Then you can use the VIN pin to get the 5v for your device. There are cases where you might want to cut the direct connection. For example, if you want to power your Teensy with a 3.7 volt lipo battery, you might want to cut the connection, and hook up the battery to VIN, and hook up VUSB to the charger. If you wanted an on/off switch on the Teensy, you could also cut the connection, and then use any on/off switch between VUSB and VIN. It is unfortunate that the VUSB pin is not directly next to the VIN so that you could use a simple 0.1" switch.
Adafruit has an on/off cable (
https://www.adafruit.com/product/1092) that can be used, but they are out of stock right now (and mostly closed down except for essential virus orders). The main secondary distributor that is still open (digikey.com) does not carry this. You could perhaps get a different switch and bend the pins, or use wires to connect to the switch.
By 'doing the USB stuff' I just meant automatically being powered on when you attach the cable.
An easier way is to get a USB cable with a switch in it or a USB switch box with an on/off button to turn the Teensy on/off, or just plug the cable and unplug the cable.
But all of this is secondary to just getting the thing running.