Thanks for your reply TIG and chrisglasier!

The advise I got made me find a good (in my opinion) solution.
I did as follows:

1. I created a texture the way i wanted it on a surface in sketchup, line by line
2. Paralel projection/perpendicular view/ Export 2D-graphic. Now i have the jpg image, taylormade exactly the way I wanted it!!!
3. Open jpg in any imaging software/crop the geometry to get rid of the marigins not belonging to the geometry/Save (one have to crop in a smart way to avoid getting extra lines at the joints)
4. In sketchup: paint a surface/edit/Use texture image/brows and select the jpg file just created
5. rescale if nessesary
   6)Voala!

I attach a geometry showing the result

Created Eternit facade texture.skp

I am modelling my house which has fibrous cement tiles (Eternite) on its outer wall front side (facade). Therefore, I want to be able to use a material/texture in the Paint Bucket Tool that correspond to the fasade. It does not appear to excist a predefined one so therefore I would like to create one myself. I would be very happy if someone would instruct me step by step on how to do this (do I need a plugin?). I attach a small model showing the facade (this is drawn line by line).

Eternit facade.skp

Hi TIG and MtnTrails,
Thank's for your advices! The hint on changing the size of the colour thumbnails made me find out how to do: Firstly; chose medium size thumbnails, secondly; let the window get as small width as possible (it cant be smaller than a certain width). Now, all colours suddenly has a logic arrangement. Any other thumbnail size or window width make the colours show up in appearantly random order.

Does anyone know how to get a better overview of the different colour options in Paintbucket?