Thermonuklear

Typos aren't dangerous, unless you make them on purpose!

ASO stands for Anvil-Shaped-Object. These are cheap cast iron anvils that look like London pattern anvils but are no good for forging. Any solid mass that doesn't deform under the hammer and the workpiece is an anvil.

If you don't have an access to a power hammer, you can effectively work on about 6" of material between reheats. Steel degrades when heated but not worked on. Also knives are not starter projects. Check out iforgeiron.com for knowledge and info.

Knuckle height is best is you have striker or do a lot of sledgehammer work. Since most smiths work alone nowadays, people riskgetting back problems due anvil face being too low.Wrist height seems to work better for most lone work. Having a separate striking anvil at knuckle height would be the ideal setting.

A little correction: ASO refers to an object that looks like a London pattern anvil but can't be effectively used as one. Those Harbor Freight cast iron nuggets that look like anvils are a good example of an ASO. Purgatoryironworks is heinous for misusing that term, if otherwise an excellent channel to follow.The video by Wayne Parris is by far the most useful of the three you linked. It has everything a budding smith needs to get started. I've taken a habit of linking it every time someone ponders about buying or building an anvil.For awesome improvised anvils(and everything else blacksmithing related), see this thread over at iforgeiron.com: https://www.iforgeiron.com/topic/52308-a-collection-of-improvised-anvilsYes, you can use a chunk of granite as an anvil. Shape is not important a...

A little correction: ASO refers to an object that looks like a London pattern anvil but can't be effectively used as one. Those Harbor Freight cast iron nuggets that look like anvils are a good example of an ASO. Purgatoryironworks is heinous for misusing that term, if otherwise an excellent channel to follow.The video by Wayne Parris is by far the most useful of the three you linked. It has everything a budding smith needs to get started. I've taken a habit of linking it every time someone ponders about buying or building an anvil.For awesome improvised anvils(and everything else blacksmithing related), see this thread over at iforgeiron.com: https://www.iforgeiron.com/topic/52308-a-collection-of-improvised-anvilsYes, you can use a chunk of granite as an anvil. Shape is not important at all! You can do a lot with a chunk of iron that has a flat area slightly bigger than your hammer.

Komea alasin, ai vitsi... Onko iforgeiron.com tuttu sivusto? Iha simona vinkkiä ja inspistä näitä seponhommia koskien.---Great looking anvil... Have you checked out iforgeiron.com? Lots of inspiration and advice for blacksmiths there.

Wonder if you could make it work with a bike dynamo?

Sorry for the super late answer! The hardness of the wood is the important part. Softer woods give you a more mellow tone, hardwoods make the instrument louder(seeing your instructables page makes me think I don't have to go into detail here :D). Spalted maple would make an exquisitely beautiful kantele. I hope you still have some left!