Ambroid sort of disappeared for a while but seems to be back. The LHS seems to sell a lot of it. Not cheap, but nothing is. I remember the 60's when my a Dad, brother and I were all building. We would go to Skelly's in York,Pa to buy it by the quart. We had a stainless steel syringe we filled. I think I have built 4-5 Ultra Sports with Ambroids
bob