Or you could simplify things a bit and create something rope-tuned like the tambora drum. I got a cheap handmade one once where the guy used this:
- A barrel or other cylindrical/drum-shaped object w/the bottom cut out (probably just used a saw & sand paper or removed the nails to get rid of the bottom)
- Some good-quality rope (it was able to withstand the tension necessary for tuning but never seemed to over-stretch)
- Some kind of rawhide (it wasn't a professional drum-head but you could easily buy a conga head on eBay or wherever)
- 2 wooden rings for rims (these were pretty cracked due to tension from the ropes, but I'm sure you could find or make better)
Here is an example of what it looks like (it's in Spanish but if u need a translation let me know lol):
http://www.youtube.com/watch?v=t6lknXZth54Now the tambora is 2-sided, and the rope was woven in and out from rim to rim in "V's". So along the body of the drum it looked like VVVVVVVVVVVVVV with each point looping through the rim. It was a bit of a pain to tune but had a great sound when it was done right (I also had to take it apart and tape up the rings a couple times; so if you want to do it this way make sure your rims are either metal or a good quality wood that can handle the rope).
So for a conga/bongo, or at least a conga/bongo-like drum, you could do something like that but one-sided. To accomplish this, you would need to have something else (where the lugs would go on a lug-tuned conga) for the V's to loop around instead of the other rim. These could probably be nails hammered into the side, then padded with tape or something like that to keep it from tearing the rope.
Either way, you're in for a lot of work, but I admire that you're trying! Me personally, I think I'd rather either save for a whole conga or buy the parts pre-made, one piece at a time to construct a complete conga.
Sounds like a fun project though, making a conga.