Subaru Outback Touring roof rail antennae clamp

I'm one of those guys that walks around the parking lot with his key fob waving in the air, desperately trying to locate his car. Now that I drive a black outback, well, lets just say the problem is so much worse... The number of black SUV's out there is staggering.

All you people that tap your horn for a cheap laugh, yeah I hate you...

However, over the years I've found that an antennae topper is ludicrously helpful to me in locating my car. My outback has a shark fin antennae though! Doh! Here's my first attempt to rectify the situation.

Hardware wise i used:
M3 x 40mm
2x M3 x 30mm
3x nylocks
2 washers
1 M5 T-slot nut. Pressed sheet metal kind (15mm x 10mm)
Antenna mast with a 5mm thread. Got mine on aliexpress for $2 shipped.

I'm testing out PETG to see how it does in the Chicago heat. So far, it's been great in 90+F weather. This might be something that ultimately needs to be cut out on my CNC, but you don't know until you try.