Tying shoe laces as a below elbow amputee is very tempting and seems to be easy to accomplish but still: it does not fall into your lap for free.
The double overhand knot allows to be locked by simple reverse pull and friction.
Pulling strings coming out of a double overhand knot in one direction will pull the knot close - reversing pull direction will lock knot by simple friction if strings are somewhat rough (most shoe laces are).
00:00 to 00:07 - start with a regular overhand knot;
00:09 to 00:12 - with string end, go around once more to accomplish the double overhand knot;
00:12 to 00:19 - using elbow and sound hand, I give *full* strength to pull the knot close by pulling string ends in the direction they come out of the knot:
00:19 to 00:21 - with gentle force, I now jam the knot by pulling string ends into opposite directions, thus friction-locking the knot to preserve the tension.
I now can take my time with this as the tension is locked by the first knot.
00:00 to 00:06 - I try to place the loop of string end 1 on top of string end 2
00:06 to 00:07 - I move string end 2 around
00:07 to 00:18 - I do the second loop with string end 2
00:18 to 00:21 - pull loop of string end 2 closer / faster, instead of using hand I fix one loop against leg/shoe using the stump
00:21 to 00:27 - pull loop of string end 1 closer / faster, instead of using hand I fix one loop against leg/shoe using the stump
00:27 to 00:30 - pull loop of string end 2 closer / faster, instead of using hand I fix one loop against leg/shoe using the stump
Remark: since my handicap is to build up tension, I solve this in the first step by friction-locking a double overhand knot. After this, I usually secure the knot / string ends additionally, either by tucking them in, or by putting a simple overhand knot around the loops.
Maybe you find a technically superior loop technique than mine, such as this:
I like this technique a lot - but quite honestly, I do have time to tie my shoes. What I don't want is the laces to come open.
The beauty of this is the simplicity, the ease of opening it back up and the elegance of using knot knowledge over actual manual dexterity. I never thought some of my almost 800 days of militia army training would come in *that* "handy" but we sure did raise some tents.
In the meantime, I found a lock system that looks OK and works very well (Lock Laces).