For the waterfall i just cut out square pieces of styrofoam and put them ontop of eachother with toothpicks untill i had the right height of the waterfall. then i used a hot blade to melt out the waterfall instead of cutting it out to make it look more natural, just push the hot blade sideways instead of cutting with it.
The sides and back i covered with black silicone to prevent leaking into wrong places (think i will cover the black sides you can see now with epiweb aswell, not sure yet).
Last i covered the front with 3 layers of grey grout mixed with a sealant, each new one a little thicker than the last, letting it dry slowly in between layers.
For the splashing i think i got lucky with the smooth slope, got it right first time (not counting the fail waterfall earlier in the thread
)
Those first 2 pics show the top of the AC unit with a tube taped to it leading to the top of the orchidarium. My fogger is only a very small ultrasonic fogger hidden in the top of the waterfall in a small water reservoir i made there. (which is quite handy since it never runs out of water, just need to make sure my aquarium water level stays up.)
Little update, i sealed the tank a little better covering all the small gaps between doors and the cover with transparant silicone. Now i get as low as 16°c at night and the day temperature doesnt seem to go over 20°c. Think this will work out just perfect for mid summer temperatures
(hope i dont kill the plants inside with the silicone smell, altho i can barely smell it inside the tank, only outside)