Step 6: Attach wires to LED leads
If the wire has been prepared with a big enough solder blob, then you will not need to add solder in this step, making it easy to do with two hands.
The button should act as a heat barrier, and protect the fabric while you are soldering. Use caution to not drip hot solder on the faux fur (acrylic melts!).
Note that the wires are oriented so that the insulated wire adjacent to the solder joint is supported by the button, rather than hanging off the edge where it will be vulnerable to damage.
Join all the (+) leads with one chain of wires, and join all the (-) leads with a second chain. Trim sharp points as needed.