Playing some French tunes and old English Maggots we find quite a few are in Em, and a D trompette can sound horrid.
As you know, retuning each time is a bit of a pain if you need to do it quickly. Over the weekend I tried to devise and make a 'push-under capo' from a piece of Iroko. Not a new idea I know, with many variations around on the Toblerone theme.
Note that you need to profile the underside a bit to match the curvature of the soundboard !
It works very well but I found that using a string-notch to help with positive and stable location instantly renders the distance from the notch to the nose very critical, giving either too much or not enough buzz. I tried to get it so that you could change note quickly without needing to adjust the Tirant substantially every time.
I hope the 3 pics are helpful. Please do note that after providing the brilliant idea for 'thumb and finger grooves' Marjorie then set about making an Italian style capo of her own which she calls 'Genus Capo Biscotti' !!
Best Wishes from
Robin (and Marjorie)