This is a guide on how to use Mann Vs. Machine part banking.

I want to buy some Mann Vs. Machine parts for metal, how do I buy these?

This is the Mann Vs. Machine banking page.

You'll see a list of bots when you click the "Buy Parts" button. Choose a bot to continue.

Here you choose the part(s) you want to buy. I've selected two Battle-Worn Robot Taunt Processors.
You can choose to pay with Metal or your Robo Parts + Metal.
I wanna pay with metal only so I press the "Offer Metal Only" button.

You're now in the queue to buy the Robo-Part(s) you selected. You might be in a queue for a minute or so. 

Now this will pop up. Click the green "Go to trade offer"

You'll now get into a trade. Simply accept the trade if everything is alright.
When the offer is alright and has gone through then the trade will be closed.

You'll now see this. You now have the weapons you wanted. Simply close it by clicking the white X at the top right of the box.

You've now succesfully completed a Mann Vs. Machine Robo Part trade! Congratulations!
It's basically the same with all the other trades, but. You can always go and check those tutorials as well.