@book_worm3 Sometimes I will separate the strands of a base string in half (so 6-strand floss becomes 3 strands) then tie it on as a regular larks head knot and it becomes its own odd base string.
If the strands can't be separated (like crochet thread) I just temporarily add an extra base string near the center as a regular larks head, so it's an even number. Then I knot around both those strings for a few rows to secure it (sometimes I loosely tie them together at the bottom so I remember it's a pair). Then leave out one of those strings and tuck it behind, like it's an unused leading string color, and cut it off after knotting another row or two, leaving an odd number of base strings to finish the pattern. If you cut off the extra too soon, the end can poke out in unwanted places 😊
I was wondering how you make an alpha keychain with an odd number of strings? I’m not going to tie the base and knotting thread together, like you normally do on alphas, so does anyone know another way?