Erson, you have reached the best teardrop site on the net. Lets see, you want to build a teardrop trailer, and when completed, I suppose you will be touring all of Europe, good for you. Actually the build is quite simple; just order a Harbor Freight trailer frame, bolt it together and start slapping some wooden members upon it. The length and width is up to you, and the smaller it is, the easier and cheaper it will be to build. Most builders rely on some sort of plans, whether purchased or obtained from this website, or perhaps an original owner/builder design.
Check out all of the related information available here. Review the Hall of Fame pictures and click on their individual build pics. I suppose you may have to jump through many hoops to finally get your trailer licensed there in Turkey. There may be some other European builders on this site that can give you some pointers. The best advice I can give you, is to come on over the pond to visit the US and attend some of the many teardrop gatherings where every type of trailer can be seen, sometimes as many as 130 all in one place.........
I realize this may not be an option, so the next best thing, is to do the research on the forum. We answer all questions regarding all aspects of a trailer build. We're here to help, all you have to do is ask. Hope all is well with you and yours over there in Turkey, and that we hear from you again and often. Good luck on your build.

Roly, the li'l ol' Southern California woody teardrop builder (among other things)