I had good success making whistle with bark i had split off of lime by slicing a line straight down the back to peel it off just make sure you wet the inside to plump the fibres when you put it back on.
Elder is great but have you considered using bamboo?
have a go with Angelica
I realise that what im going to suggest is larger than what you want but im sure the same procedure could be scaled down. Afew years ago i made a didgereydsoo by selecting a piece of dry branch about the thickness of my arm , and splitting it length ways . then witha gouge i hollowed out each half without touching or altering the outer edges of the split so that when the two halves are put back together they matchup perfectly. Apply the glue , reassemble the halves and bind with a loop of rope and tension it like a garote the more of the tensioning loops you use the tighter the join and the more invisible the join. Hope you find this useful.
I tried with a hogweed stem (pretty dead so not a danger), it worked but it was quite hard to get a clean edge for various holes. Do you think angelica would dry any harder?
Leo
:-0
Really, really don't do this. People have died from inhaling some of the irritant sap.
I got some on my ankle once - brushed against a plant. The bruising from the chemical burn travelled down through my foot, turned my sole black. The GP seriously considered packing me off to A&E, the swelling was coming up so fast and combined with so much bleeding under the skin.