Material Choice

I have always made the marble tree out of wood. In theory you can also make it out of acrylic plastic sheet. I have done some experimenting here, and it should work, but from what I can tell, acrylic does not make as nice a sound (wood really does make a pleasant xylophone sound, acrylic is ‘duller’).

So I recommend wood. The unmodified plans are for 1/8” plywood. Home improvement stores (e.g. Lowes or Home Depot) typically don’t sell plywood in this thickness, you have to go to a ‘real’ lumber yard. In the Seattle area, Dunn lumber sells a variety of 1/8 in plywood (in particular they sell 3’ x 8’ oak ‘Door Skins’ that I have used personally). In Seattle there is also Crosscut lumber which sells an even bigger variety of very nice wood (in particular thy sell 3mm (close enough to 1/8) 'baltic birch' 5’x5’ sheets). You should be paying somewhere in the neighborhood of $.70 to $1 per square foot, but you may be buying as much as a 4’x 8’ sheet.

Finally, if you don’t want to bother going to the lumber yard, you can buy the correct plywood online at www.amazon.com. I have seen 10 sheets that are 1’ x 2’ sold for about $40. Just search for ‘hardwood plywood’ and look for 1/8” thickness. Note that these instructions have laid out the pieces so that they fit on two 1’ x 2’ sheets of plywood. You can use smaller pieces of wood (e.g. four 1’ x 1’) if you fiddle with the layout, but I leave that to your ingenuity.

If you minimize waste, the marble tree needs 3.5 square feet of material, however, here we ‘round up’ to needing two 1’ x 2’ sheets of plywood, so you end up using 4 square feet for one marble tree. Thus a 3’ x 8’ door skin can make 6 trees, and a 4’x8’ sheet will make 8.

Note that the cutter plans are designed for specifically 1/8”. However often what you are buying is just ‘close’ (e.g. 3mm, or 2.6mm or whatever). This is OK BUT YOU MUST SCALE THE DESIGN TO USE IT. The design has ‘slots’ in it that need to be the thickness of the wood, so if your wood is thinner, it will only fit ‘sloppily’. You fix this by scaling the design before you cut it (See compensating for thickness below). If you want to avoid this complication, simply make sure you buy TRUE 1/8” material.

Finally you can buy ¼ plywood and scale up the design, all the pieces will still fit in a 24” x 18” laser cutter. It will make something twice as big, which will stand about 3-4’ tall (and you will probably want to use big marbles).