Prepare a place to pour your honeycomb. It will need to be a flat, rimmed surface lined with something non stick. I use a rimmed baking sheet with a piece of nonstick foil covering the whole bottom. You could also use parchment paper.
Put water and sugar in a pot on medium heat. Put lid on top. Wait until you hear simmering, then lift lid gently. If you see only clear bubbling liquid, keep the lid off. Otherwise re-lid, wait a minute, and check again.
Here’s the hard part: do not stir or agitate at all. Do not even touch the pan unless necessary. If you have a candy/frying thermometer, attach thermometer. This step (adding the thermometer) is optional.
Be patient. Cook to 300-310 °F (hard crack stage). If you do not have a thermometer, wait until you see sugar start to turn golden. When the edges of the pan are brown, take it off the heat.
Take the pot off the heat and take it to your work area. Put the baking soda into the pot and stir. It will boil up violently. You need to stir enough to distribute the baking soda but slowly enough so you don’t go over the top of your pan. Pour the mixture onto your pan and allow to cool completely.
Cleanup from sugar making is easy but slow. Simply soak in warm water. Thicker bits might need to sit overnight.