I cobbled this recipe together from various sources many years ago. I have never got around to trying it, but it has to be done and you are the one. It possibly sounds quite lethal and I take no responsibility for your subsequent blindness if you choose so to do.
Wipe a very large ripe marrow clean with damp cloth, then saw a piece off the top end. Set this cap aside and scoop out all the seeds and pith with a long handled spoon.
Press demerara sugar into the cavity and fill it right up to the top. Pour in activated wine yeast, from home brew shops, and add the juice of an orange. Replace the end of the marrow and seal with gaffer tape. Suspend the marrow over a bowl and leave in a warm place.
After a couple of weeks unseal the end of the marrow and top up with more sugar. Some of the first lot should have been absorbed into the flesh of the marrow. Replace the cap again and reseal. At this point you may want to hang it in muslin before the whole lot collapses.
Leave for a few more weeks until the marrow starts to drip from the bottom into the bowl. All the sugar should have been absorbed by the flesh of the marrow. Spike a hole in the bottom and allow the liquid to drain into the bowl. Strain it into a fermentation jar and fit airlock.
Keep at least three months and up to a year. The longer you leave it, the stronger it will become.
If you have been brave enough to not just make it but drink some and still have your vision, please let me know and I will gladly buy you a very decent lunch for the opportunity to taste this hillbilly nectar.