Just completed a batch.
I used 3 pounds of butter and the amount of leaves and stems it takes to stuff the cut off legs of large panty hose, 8-12 oz's. Simmered them together in a large roasting pan half filled with water for 8 hours while stirring them and squeezing with tongs occasionaly. I removed the stuffed nylons, squeezed them back into the roasting pan by hand using heavy rubber gloves. Set the roasting pan off to the side to cool and put the nylons into another large pot half full of water, enough to cover the nylons, simmered them another hour, squeezed the nylons and poured all of the liquid into a bowl to cool and then repeated one more time. The second and third pots each gave me about 10 grams so it seems worth the effort. Using nylons to contain the pieces certainly worked for me. After removing the chilled butter from the roasting pan I cooked barley in the remaining water to pick up the left over butter bits and the dissolved milk solids. That's for the freezer and winter soups.
Before I baked with this, to get a feeling for its potency, I made tea with it. I brewed tea and removed the bag, added a heaping tea spoon of butter, and kicked back, nicely and for a long time as it turned out. Now I know if I'm planning on 16 one per voyage brownies I need 16 heaping tea spoons of my butter and then top it off with regular butter to meet the recipe requirements. Or I can use 8 spoons and eat 2 brownies. You can skip the tea part and just lick it off a measuring spoon but by this simple test you'll ultimately end up with far more predictable baked goods. I found it took close to two hours for me to peak, your results may differ.
For next time I'll cut the stems into 1-2 inch lengths and prolly split the big ones. Nylon is amazingly tough but while your long stems might not go through the nylon they're awkward when you're squeezing.
For sure I'm giving the next product a week long water cure before I start. I've done one on bud and liked it, just never occured to me to do it on the trash. I'd stuff the nylons first, before the cure. I'm doing this to reduce the water soluble material that contributes greatly to the smell once you start to apply heat.
I bought a Procter Silex single burner to do this in the garage. They use a self setting thermal overload switch (that they don't tell you about) that requires your constant attention until you bring your mixture to a boil. I found midway on the dial kept me at a nice simmer with no thermal cut offs once &*#$@#? boiling was achieved.
The second and third cooling pots should have the smallest surface area you can manage. The thicker the cooled solid butter is, the easier it is to remove. You folks doing a single stick should think about that. When the butter skim is thin, removing it is like pushing string.
Remember most commercial butter is about 80% fat, that other 20% is water and milk solids and that part's all going into the water you're cooking with, expect to finish up with noticeably less than you started. A regular maker told me she gets about 75% back. Cooking oils are 100% fat but they also take a lot more chilling to turn solid and solid fat is much easier to separate from the water.
If you've got pets be careful with the leftovers and the dirty pots. Butter out in the open is hard for them to resist. One of my little guys grabbed enough of some unnoticed thing to spend a few hours in my lap doing a south asian head bob. Not fun at all.