Complete the vending machine activity diagram using PlantUML

Sure, here's an example activity diagram for a vending machine using PlantUML:

@startuml

start

:Insert money;
if (Selection made?) then (yes)
  :Dispense item;
else (no)
  :Refund money;
endif

stop

@enduml

This is just a basic example, but you could expand on it to include more specific actions and conditions based on the requirements of your vending machine.