Cob (tapered threaded rod) to hold a Hemingray No 21 glass insulator

I made this to mount a glass insulator on top of my TARDIS little free library. The cob (the tapered threaded rod) cantilevers from an 80 mm x 80 mm x 5 mm mounting base. The cob is a customized version of the parametric tapered thread coupling at https://www.thingiverse.com/thing:3544909. It uses these options:

type = single collet
view = all parts
center_length = 35
center_decoration = none
center_decoration_outer_diameter = 10
center_decoration_height = 8
thread_edge_flat_height = 2
nut_tolerance = 0.2
collet1_inner_diameter = 10
collet1_outer_diameter = 32
collet1_length = 45
collet1_pitch = 6.2
collet1_taper = 0.05
collet1_cutouts = 3
collet1_cutout_widths = 1.5
collet1_cutout_depth = 40
collet1_top_angle = 45
collet1_bottom_angle = 45
collet1_nut_outer_diameter = 19
collet1_nut_height = 10

I merged the tapered thread coupling with an 80x80x5 rectangular base, and added 6 holes: four 3 mm holes near the base corners for screws to attach the base to a substrate (the wooden top of my little free library), one 5 mm hole radially on the throat near the base through which to lead a wire, and one 10 mm hole axially through which to lead a wire by an alternate route. I plan to add an LED light in the top of the cob, powered by a solar panel and battery. I will superglue the glass insulator to the cob to make it harder to steal. When screwed all the way on, the insulator stands about 5 mm proud of the base, so if you want it snug, reduce the center length to 30 or 32 mm. To keep bugs out, seal with silicone.