The guitar is made from one plank of hardwood. I used maple, but you can, in principle use any well-seasoned hardwood plank. Mahogany, walnut, cherry, oak, beech, alder, basswood could all be used just as well as any tropical hardwood I may not even have heard of. Therefore, my standard answer to the question "Can I use this particular type of wood?" is inevitably, "Why not? Give it a try." Even softwood timbers like spruce or pine are conceivable, although hardwood is preferable. Each piece of wood will sound different, but it is practically impossible to predict exactly how. You would have to build several guitars and fit the same electronics, pickup and strings on all of them to be able to compare them. But why should you anyway? I'm quite sure you'll love the sound of your unique lap steel guitar.
Use only dry wood
The wood has to dry before use; otherwise it will warp and not
maintain its shape over time. For instrument-making the moisture
content ought to not exceed 8% (just in case that you have access
to a wood moisture meter). There is a very simple method of making
sure that the wood is dry enough: put the pre-dried guitar plank
into a room where humidity is below 50% - this can be your workshop
or any other room with constant humidity. Weigh the plank and note
its weight and the date of weighing on it. Do this once a week
until the weight remains constant (i.e., the piece doesn't lose
any more weight). This is the point when the wood is in balance
with the room and is ready for use.
Wood moisture content
The weight of a piece of wood always includes the weight of the
water contained in it. The relative wood moisture content is the
ratio between the weight of the water contained in wood and the
fully-seasoned wood. The approximate wood moisture content can be
determined with electronic measuring instruments measuring the
electrical conductivity of wood, which is directly linked to the
wood moisture content.