It will now become apparent why I had you leave the exterior of the stalk rough, and uncleaned. To bond the two halves together you can either use wood glue, as shown here above, or you can use the same two part epoxy resin as used in the coating of the interior. These days I am prefering the resin. Regardless of which you use you will see that this is the messy part. By leaving the exterior unfinished you don't need to worry about dripping all over it.
Make sure you have enough hose clamps (shown to the left of the didj) to clamp the two halves together with a spacing between each of 3 or 4 inches. Make sure you have the right size of clamps to accomodate the different diameters you will encounter along the length of the stalk.
Put a generous bead of resin, or glue, along the whole length of the two sides of one of the halves of the stalk. Don't worry about the mess inside or out. Just make sure you get a lot on the edges.
Next fit the two halves together and line up the edges and ends, top and bottom, as shown in the second photo above.
A special note for large bells... I do not have a large hose clamp to accommodate most big bells. Additionally these bells tend to have more uneven surfaces so a hose clamp would prove difficult to use anyway in this area. So I use a strap clamp. This consists of a long, wide strap that can be hand tightened to a point then it has a ratcheting device that I can tighten with a screwdriver or wrench. I have used one of these in the picture above. You can see the long tail of the strap along the right edge of the photo.
Construction of an Agave Didjeridu