Picket fence cat door or dog window

Circular porthole frame attaches to a picket fence to allow cats through, or dogs to lookout.

Designed for 5/8" thick fence pickets which are fairly common in the US. Uses 6 M3 30mm screws to attach the two halves together. 25mm should work too if your fence is not thicker than 5/8".

There is a cutout in the inner rings to allow water to drain, specifically to reduce splitting during freeze/thaw cycles. Align the drain holes when installing, and orient downwards. Each side has a flange that nests into the other side, and grooves to keep things aligned. When installing, trace the widest flange and cut with a jigsaw. Be sure to leave enough “meat” on the picket for the screw to pass through. Pre-drilling the screw holes is recommended.

Print with PETG or other materials that do well in the weather.

The portal pictured is 250mm diameter. I've included a 200mm diameter variant for use with the mk4s. 

The attached fusion 360 file is fully parametric, so you can adapt for different hole widths, fence thicknesses or screws.

Room for improvement. (things that would be nice to have, if i started all over):
Adding a receiving nut pocket for the M3 screws would improve connection

Or, instead of metric screws, the  screw holes could be adapted for weather resistant decking screws that would grab the wood from each side. The drain location would have to be adjusted.

The screw dimension variables are all separated. Tying a master variable to multiple screws variables, m3/m4/m5 would make it easier to adjust.

Please post any makes - i love seeing other peoples critters!

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