A birthday card for a sheep owner. Stitched on felt with a CD inside. The sheep was digitised to stitch on card and I wanted to beef it up a bit so I stitched the outline with two shades of grey thread in the needle together. The darker one is threaded through the spool of the lighter one. This causes the threads to twist together as they run through the machine giving a tweedy effect to the stitch. (See close up) I had to hold the lighter thread spool above the darker one while it stitched. Now I know it worked, I'll be thinking of a better way to arrange the spools!
I used to wind a bobbin with two shades, for bears, afraid to have my construction knocked over when embroidering.I used a thread stand, an old small bucket with a hole punched in the bottom. Not the most stable contraption, hence the bobbin. The fill had to be density 7 or so, would have to look at the designs to know, so the stitch count was relatively low. Which I liked.