After the spring semester I was finally able to finish the last planned elements of the horn I’ve been building using parts obtained from Rick Seraphinoff. He sells a version of the same horn, described here. The main info is:

The Courtois orchestra horn is copied after an original [ca. 1820] in excellent condition with original crooks that was acquired by Seraphinoff Historical Instruments in 2012. The bore is slightly smaller than the Halari and Raoux models. Crooks are made with the original smaller sized mouthpiece inlet for use with historical mouthpieces. When using a modern mouthpiece with this instrument, it is recommended to turn down the shank to fit properly into the smaller inlet.

The larger bell throat of this model gives it a warm sound and solid low register. Bell diameter, 28.5cm (11 7/32″) Bore, 10.92mm (.430″)

The early part of the build is described further here. I think it came out great! I did make it to take a modern shank mouthpiece. Took me nearly a year to complete to the version seen below.

Seraphinoff supplied all the tubing but, other than the tuning slides and the bell itself, all of it was straight. All the work seen beyond that I did in my garage shop. Working around counterclockwise, there is a Eb crook, E crook, F crook, G crook, a long tuning slide, and a coupler that takes F down to D (and Eb down to C, with the slide pulled). All seen slightly better in the next photo.

I’m really happy how it came out! It is very interesting and enjoyable to play — every horn has a bit different character — I especially enjoy it in Eb. The high range is better than on any other natural horn I have access to.

I could imagine making a few more parts — an A crook and a Bb crook would be handy, as would a way to get the horn down to Bb basso. But I’m very happy with what I have, and as it all fits snugly in a case maybe I should not make more parts!