Developing a tool is a circular process - designing, making, testing and then back around again until all the parts are right. I usually have help evaluating tools from people with expertise in using them. Like George Sawyer. George makes Windsor chairs and approached me because he had an old inshave he liked but could not find a comparable commercial one.
He tested six prototypes before giving his nod of approval. Inshaves have a lot of curves and angles. It turns out that each curve has a reason and each angle has a sweet spot. It turns out the bevel needs to be just the right length - to long and the tool can not cut a nice radius, too short and it is unstable. Also the blade needs to be thick enough not to flex and the handles need be comfortable while pulling on them which, it turns out, is a different shape than a handle you hold while pushing or striking.
Each tree species makes wood with its own characteristics.
White ash and hickory split easily but are very resilient when bending which is great for ax and fro handles.
Sugar maple splits moderately easy and is tough as nails - good for any kind of handle.
I like to use black cherry for my small handles. It is softer than the other woods but takes a really nice finish. Most of the handles with a burned finish are cherry because I like the rich undertones that show through.
Lately I have been using hop hornbeam for my struck handles. It takes impact especially well.
I mostly harvest handle wood myself or get it from neighbors. But hickory does not grow here in the mountains so I get it from the Lake Champlain Valley where it is a little warmer.
Most of the smaller tools and all the cutting edges are made of plain carbon steel. The carbon content makes it so I can heat-treat them to get the right hardness.
The bodies on most of the larger tools are made of mild steel for a few reasons. The first is that I can not get the kind of carbon steel in the size I need to make the whole tool. So I forge the body of mild steel and weld in a carbon steel edge. Mild steel is also easier to forge, especially in larger crosssections. An additional benefit is that having part of the bevel out of mild steel makes the tool easier to sharpen.
I purchase some new steel and get some at the scrap yard. All cutting edges are made with new carbon steel which, when heat treated in my tempurature controlled oven, yields consistent performance.
In the accompanying image of my first carving ax you can see these two steel layers clearly.
My carving tools come sharp. As noted in the descriptions, most complete carving tools come with a handle and sheath. Just blades come with a temporary covering to keep the edge from getting nicked.
Any tool that is big enough comes with my stamp on it and a batch number - usually in roman numerals
I am currently making my sheaths out of elk rawhide.
All my tools have a non-toxic linseed oil and bees wax finish.