I used 10mm plywood. before milling i cutted it exact to 60×30 cm. Every mm counts.
Put your material on the board. Take care that you are parallel to the down wasteboard edge and mark the edges of your material on the board to have the exact postion.
I was using a 60 degree v-carve bit.
Carve Side A
After done with side A.
Put double sided tape on your carved areas.
Flip the material on the wasteboard and fix it on the exact same positon. Do not move your router while doing this. The tape will hold the carved parts.
Carve Side B
take your time and bring everything together by wiring up the parts.
thats it. have fun