I designed a D-handle and Latch Pull Down for my newly installed fence. The D-handle should work on any plastic fence. The Latch Pull Down may not fit your fence hardware so print at your own risk. The hole on the latch was 9.7mm, the angle of the slope on the latch plate is 116 degrees, the thickness of the metal was 2.84mm.

Here are the details.

D-handle for the fence gate:
The white handle has a pocket for 2x strips of 1/2" VHB Automotive 3M double-sided tape. Basically a slightly over 1" wide pocket that goes along almost the entire height of the part. When installed you won't be able to see much of the tape. I used painter's tape to cover the pocket while I primed and spray painted the part. Then I removed the painter's tape and applied 3M Adhesion Promoter to the plastic and adhered the VHB tape to it. I cleaned the fence with rubbing alcohol before adhering the gate handle to the fence surface.

Latch Pull Down:
This part sleeves onto the existing latch and then the plug joins the two pieces. A 1/16" x 1" cotter pin secures the plug so it does not come apart. The parts all barely slip fit so its nice and snug. In the image, I did not spread the cotter pin but you can. I want to be able to remove this assembly if for some reason the UV fades the part or if the filament doesn't hold up. It fits snug and is unlikely to come out on its own.

Please note the print orientation I used in one of the photos. In the middle of the design, I realized there was a better orientation to print this with minimal supports so please ignore the default orientation. You're welcome to try however.

At 25% infill, the Latch Pull Down was 1 hour 44 minutes, the D-Handle is 4 hours and 35 minutes, and the Latch Pull Plug is 12 minutes on an Ender 5 Pro. Supports are minimal if printed in the orientation I have in the image.

3M Adhesion Promoter
https://www.amazon.com/3M-VHB-Universal-Primer-Nitrile/dp/B07K1TRBRY/ref=sr_1_1?dchild=1&keywords=3m+vhb+primer&qid=1626398082&sr=8-1

3M VHB Tape - 5952 0.5 Inch Double Sided Tape (12.7mm X 4.8m)
https://www.amazon.com/gp/product/B08GFRT9D3/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

Cotter Pins
https://www.harborfreight.com/555-piece-cotter-pin-storehouse-67558.html

Good luck!