I created this basic bracket to hold a thermometer to the ceiling of my V400. I was interested in being able to monitor the temp and humidity after enclosing the printer. I left the bracket open to allow these cheap humidity thermometers to be as accurate as possible. This example is printed in PETG, but PLA should be fine since the temperatures never exceed 120F. 

Amazon.com: Pgzsy 12 Pack Mini Small Digital Electronic Temperature Humidity Meters Gauge Indoor Thermometer Hygrometer LCD Display Fahrenheit (℉) for Humidors, Greenhouse, Garden, Cellar3 : Patio, Lawn & Garden