But it's not the way to make a quality piece?
If you put all good steels in the canister you can make a good piece of steel to work with--but it's probably easier to just get a good piece of steel to start with than to deal with the hassle of the canister. And at the same time, you can eliminate the potential issues that can result from a bad forge weld.
Do commercial knife firms use the other styles, like sandwiches and tacos? Or are the knives from one type of metal? I get the idea of a sharp edge and flexible blade.
There are commercial firms who make laminated steel blades of various types. For example, it's not uncommon for good Japanese cutlery to be made up of one layer of hardenable steel that forms the cutting edge with another layer of softer steel that provides additional strength combined into a single-bevel blade. It's important to be able to recognize this kind of knife as sharpening it like a conventional two-bevel knife will put the softer steel on the edge.
If you have a very good steel, one that has good edge-holding, is tough and hard to the extent that is required by the intended application of the blade, then as long as you can afford it, it makes sense to make the whole blade out of that steel. If you want to minimize the amount of high-end steel used in a knife without sacrificing cutting/edge-holding/toughness performance, or if you want to use a steel for the cutting edge at a hardness level that makes it more brittle than is ideal, then going with a laminated design can provide some extra strength--some insurance against breakage. It won't keep the edge from chipping, but it can keep the blade from breaking.
Also, if the application of the resulting blade makes really high demands on the performance of the steel (generally hardness and edge-holding performance must be balanced against the ability to resist breakage) then a laminated steel might be a good choice because it lets you have both at once by combining the properties of both of the steels used in the laminate.
So, is it practical? Well, it CAN be. If you poke around, you can find some knives made of laminated steel where the two steels in the laminate have pretty similar properties. That's not really doing anything practical. And you can find laminated blades where the steel used for the edge really has enough toughness for the application--so there's no need to try to bolster it by adding layers of another type of steel. Obviously not so practical there either.
In addition, one can use differential tempering/hardening to achieve the same kind of benefits that are provided by laminated steels. So one might make a blade and leave the back relatively soft while the edge is very hard. Pretty much the same kind of an effect as you'd get from a laminated steel.
But I do think there are some applications where laminated steels make practical sense.
I feel like I should mention that I don't think this post is a very thorough treatment of the topic. There are other benefits of laminated steels (potentially easier sharpening) and other disadvantages too (delamination, galvanic corrosion), but maybe it's not misleading or overly simplistic. Also, it's worth noting that I have no experience or education in metallurgy or blade-making.
