Hi Costumeclaire. Nice vases!
I just wanted to comment on he fact that you put the leather in boiling water. Since I've made a few pieces of armor using "cuir bouilli"/ "boiled leather" as well I did some research on the larp costume making forums and got the following info:
the "boiled leather" name doesn't actually come from the fact that you boil the leather, but from the fact that tiny air bubbles leak out of it when you immerse it in water, creating the effect of boiling, even in cold water
the hotter the water in which you put the leather, the harder it'll be when dry but also the more brittle.
For armour I/larpers usually use warm tap water and have water of about 40°C (104°F) and leave the leather in the water until all the bubbles are gone. When it's put into shape and left to dry it stays in the same shape and is still pretty supple (meaning It can be bent to work it without breaking it and it goes back into shape once released).
Just my 0.02€.