Thx for your comments!
@Trov Yes, thx again for your idea!!
@Corvus Thats a simple picture frame. I glued the backside to it and fixed it with the metal pins that are in the frame. Then i used some cork and glued it... and then i took a square base, drawed it's measurements on the positions I wanted the minis to be... after glueing the hard work began

I knifed the holes out, and kinda scratched the cork out of the holes... if the base wasn't fitting I just scratched out some more.
And thats it - hope I could help you!!
@mahon Yeah I'll try to do the grass more uneven. It is already painted and highlighted, which doesn't show that nice on the picture.
Ok so... looking forward to get some more feedback

And i'll continue the work ASAP