Miniature art always fascinates me and I too tried, but not at microscopic level like 'grain' or 'pencil head'. I tried some what macroscopic arts on chalk and crayon. I tried carving two interlinked hearts with part of a single crayon .
One heart is in XY plane (let us say), the other heart is in XZ plane.. Ohhh.. I'm not so good at explaining this.. Have a look
This is one heart and there is another heart in the perpendicular plane. You can observe part of it in this image. If it is turned 90 degrees, other heart will be visible like below