I've been here before!
The steam or boiling water event is great fun and easy enough in ash [or hickory if you are in the US].
The trick is to form the side to side dimension accurately and just do a gentle excess in the fore and aft dimension.
Bill and the others will know that the 'former' is easy enough to make. It needs to be deep enough to avoid reciprocal bending, too!

To make the external or female support to the chosen plan view involves more material than a male mould.
You can do a wrap-around internal former alone, but I find these are inclined to splinter the 'hoop' in the stretching of the wood fibre. If you do the latter, use corner supports on the outside as well. If you are smart, you will make the blocks with clamp-able faces to allow you to really squeeze the shape accurately.
Over-bend the final angles as the spring-back is 3 or 4 degrees after cooling.

If you laminate out of ash, get each face/layer sanded and flat before gluing. Edges don't matter till afterwards. They bend better with damp heat, too. If it is too wet, use a steam-iron to dry off the excess.
Glue: use a resin [epoxy or two pack] or a polyurethane adhesive. Try boat builders and marine suppliers for the best ones. Forget PVA!
My local boat builder allowed me to use his steamer! It cost me a couple of hours learning about boat-building.
Make three and sell them on!