algebraic3d

solid cubeair = orthobrick (-0.5, -0.5, -0.35; 0.5, 0.5, 0.65);
solid cubebigger = orthobrick (-0.5, -0.5, 0; 0.5, 0.5, 0.4);
solid cubesmaller = orthobrick (-0.5, -0.5, 0; 0.5, 0.5, 0.3);

solid cylbigger = cylinder (0, 0, 0; 0, 0, 1; 0.055);
solid cylsmaller = cylinder (0, 0, 0; 0, 0, 1; 0.05);


solid core = cubebigger and cylsmaller;

solid coilhole = cubesmaller and cylsmaller;
solid coil = cubesmaller and cylbigger and not cylsmaller;

# solid filler = coil and core;

solid air = cubeair and not coil;

tlo air -col=[0,0,1] -transparent;
tlo coil -col=[1,0,0];
# tlo core -col=[0,1,0];