DIY Telrad Dew Heater and Shield

My Telrad fogs up very easily - it's the first piece of all of my telescope gear that suffers from dew.  Often, it's the only piece of my equipment that has issues with dew.  I didn't want to spend a ton of money on a custom dew heater for my Telrad, so I decided to make one.  

I won't provide a tutorial on the electronics.  I followed a modified version of the plans found here:  https://www.dewbuster.com/heater-resistors.html  My particular setup is using 5v USB power to power 3 10 ohm resistors wired in series.  I used high temp silicone tape as the backing and wrapped everything in HD duct tape.  Once the heater component was assembled, I used hot glue to attach it to the plastic (we'll have to see if this actually works for the long term).  You assume all risk of creating a heater.  If you screw it up, it could result in major bodily harm or death, and could result in fires causing damage to your scope, telrad and anything else in the vicinity.    By using this design, you assume all associated risk.  

The only tricky part of the mechanical component assembly is the brackets.  I had to custom make brackets out of aluminum angle.  I've included a drawing of the brackets.  The only truly important dimensions are the placement of the holes.  Once the brackets are created, they screw to the Telrad through the plain holes using the original Telrad screws.   The flip cover attaches to the brackets using M4 screws and nuts.  Place the m4 screws through the holes in the flip cover, and thread them into the tapped holes in the brackets.  Don't tighten the screws down.  You want the screw to protrude through the bracket far enough to be able to place a nut on the screw, but you don't want the screw to tighten on the flip cover - the flip cover should be able to rotate freely.  Once the m4 screws are situated, then tighten the nut onto the bracket to lock the screw into place.  The pictures show how things should be arranged.  

I'd suggest using a higher temp plastic like ABS for this project.  PLA would probably work for me with the temps I'm seeing, but PLA has a pretty low glass temp so I didn't want to mess with it.