Making the instruments is pretty simple. The most difficult part of the entire process is getting the materials in the first place. Finding gourds of an appropriate size in the states is challenging (my efforts were unsuccessful, although I did get smaller gourds from farms in Florida and North Carolina that would be good for soku/njarka). Anyway, here are some photos of the process with brief descriptions.
Step 1: Assemble materials.
In a clockwise direction starting at 11: Antelope skin, high guage fishing line for strings, wooden bridge with holes drilled for however many strings you want (I did 6), bamboo rods to insert under the skin/on top of the gourd, upholstery tacks to secure the skin, neck with guitar tuning keys to tune the strings, gourd with top cut off and insides scraped out, 2mm accessory cord to counter-tension the bridge against the taught strings, fabric or cord to tie two of the bamboo handles to the neck (see below where I just used 1mm cord), knife and razors to shave the skin and make small incisions for the bamboo rods.
If I were a better wood worker/had better tools I'd smooth out the cuts when attaching the guitar keys.
Step 2: Finding the area of skin you want to use, cutting it, soaking the skin, cleaning it, and ripping off some of the under-layers that prevent it from being as elastic as possible.
Step 3: Attaching the skin.
Step 4: Insert the bamboo rods.
Step 5: Secure the parallel bamboo rods to the neck.
This is what the ngoni looks like so far (below). Eventually the skin dries around the gourd and becomes crispy again. You can trim the skin to make it look neat but I liked all the directional lines created by the edges of the skin and on the top (couldn't get all the layers off, which is the difference between the colors on the skin).
Step 6: Attach and secure the bridge.
This step is a sequence of back and forth between the strings and the cord used to counter-anchor the bridge. First I loop cord around the head of the bridge and the butt of the neck that sticks out of the bottom of the gourd, angled back. Next I thread two strings through the bridge up to the guitar tuning keys and tune them till they're fairly taught. If needed I'll adjust the cord because even though it is capable of holding hundreds of pounds of force, it has some elasticity to it and eventually will be pulled forward.
Step 7: Tune the rest of the strings and finalize the bridge attachment.
The light purple cord on the left and right of the bridge doesn't really do much after the bridge is pulled into place from the front and back, but initially it helps keep the bridge upright as a left or right string is tuned tight. Again, since I climb and like knots I get overly-fancy with the finishing touches. Something much simpler will work. The black spot on the bridge is a spot pickup available at guitar shops, commonly used to amplify violins or other acoustic instruments. It gets really good sound.
And the finished product:
It takes a few days to fully tune the thing, since the nylon strings continue to stretch. Eventually they max out and it will stay in tune and taught. I like the strings to be super taught to get good harmonics that add little "pings" among the other notes played. I've tried using guitar strings but don't like how they sound. I also bought a pack of six strings and used every one of them. It might have worked better to only buy one guage so they have mostly equal tension and don't sound like plucked rubber bands. If anyone tries let me know!
Here's a good alternative video and perhaps more "authentic". His final product looks like what you see in the big market in downtown Bamako. I guess mine is in the style that Sekou puts them together.
Here's my new house and it's amazing view: