for outdoor use, ASA would be the best material. looking at the geometry of what you posted, I think if you want to pay someone with a lathe or a CNC lathe to make the top and bottom die, this would be a good design for injection molding. you could maybe do some kind of resin casting at home instead of injection molding. any FDM printer will have layer lines. this looks like a staircase with 0.1mm layer height. sls or sla would be better to avoid the layer lines but I think you would probably only use sla to make a posative plug for casting.

as for the material strength, they are similar. you will not make the part thin like paper or thick like ceramic. probably something in between. the 3d printing company you use will probably tell you if the part is too thin to work. if it is too thick they will print it anyway for more $.