Marcel, I get it at Praktiker - a home store! They recently have taken it into sale. And they actually have developed quite well. The 2mm birch ply is a really fine one designed for model craft air planes: webshop selling this aircraft plywood You can get it from 0.4mm(1/64" - 3 layers!) up to 18mm(3/4" - 24 layers!). It comes in best quality, no faulty spots or so. Not cheap at all, but great to work with. I'm paying around 34Euro/per meter for the 2mm ply.The items sell well, so it's worth it.