I recommend PETG as it will handle the outdoor temperature well and mine have been perfectly flexible which is great for getting them in place but they hold their position plenty strong. 1 clip every 2-3 feet is fine but you can do more depending on the weight of your project. Here are my Print settings but these only take about 10 mins on my .6 nozzle so they print pretty quick easy to experiment with!

I have included the step file if you have different length trim then just adjust the longest part it is currently 76mm.

235 Hot End / 70 Bed

No support

3 wall count

(these next 3 settings will depend on your nozzle size, I use .6 most people use .4)

Layer Height .48

Initial layer height .6

Line width .72

25% Cubic infill

NO Cooling