I did it! The entrance door has 'frosted glass'. Didn't do it the way I had it originally planned, but it worked anyway. I couldn't find the etching spray for glass, although I managed to find the article on it, but when searching for it on Google I discovered a kind of spray paint that produces a similar result. So I went in search for the hardware store that was supposed to sell it and voila: frosted glass paint was on the shelves! I have to be very careful now not to scratch the surface when finishing off the door, but am very happy with the result so far.
And how did I do it, you may ask? Again I have been a bit slack with taking pictures, but the design on the perspex was done with stickers for card making purposes. So it was just a matter of finding the right stickers (and since I make cards too I had plenty to choose from) and stuck them onto the perspex. Afterwards I had to find the right time between the spray paint being touch dry and not too dry, in which case the paint would peel off together with the sticker. Of course I tried it all out on a glass bottle and other plastic containers before I went ahead with the door itself.