A xylophone is perhaps the easiest build-it-yourself melodic instrument project. A true xylophone is made from wood, although they can be made with metal striking bars. The basic xylophone design is simple and the construction is straightforward, making it a satisfying project for those with basic woodworking skills.
Hardwoods, particularly maple, produce the most pleasing, sharp and sweet tones. Use clear, knot-free and flawless sections of lumber. A 14' length of 7/8" x 3/8" actual measurement hardwood, cut in 30 sections ranging from 4" to 8" will provide enough blocks for a 2-1/2 octave chromatic xylophone. The size of each block will determine the pitch it produces, so if you want a larger or smaller xylophone, you'll need to experiment to get the results you want. Consider measuring the block widths and lengths on a ready-made xylophone to speed the process.
Those with a good ear for pitch will be able to tune their xylophone components by comparing the pitches to a well-tuned piano. A digital tuner, however, is the easiest, most exact way to precisely check and adjust the tuning on your xylophone. Hit the component while watching the tuner gauge---if the needle points to the right of dead centre (pointing straight up), the component is sharp to your desired pitch, or too high, and needs to be trimmed shorter. If the needle points to the left of the centre, the component is flat, or too low. Since you can't add material to the wood, you'll need to start over with a longer piece of the material to get the desired pitch.
Traditionally, a wood support frame is used for a xylophone. The wood allows the components to vibrate, but doesn't ring or rattle along with those vibrations. A simple wooden rectangle frame, perhaps with rubber or cork applied to the bottom to prevent the xylophone from moving as it is struck, is all you need. Use wood screws at the corners for the most secure joint, as loose joints will rattle when the xylophone is played.
Glue a cushion strip of cork, rubber, or felt along the top of the wood frame, and then rest the tuned components on top of it, with the longest, lowest components at the left side, and then arranged longest to shortest to the right. Space the components evenly apart.
There are many methods to secure the tuned components to the frame. For a folksy look, tie each component firmly but not tightly to the frame, using jute or macramé cord. Or, you can string the components onto jute or macramé cord---drill a hole through each end of each pipe or wood component, from the right side to the left, and then thread the cord through. Finally, the classic technique for a wooden xylophone is drilling a hole at the centre of each end, from the top down through to the bottom, and hammering in a nail, or installing a wooden peg, through each hole into the frame, spacing the components as described above. Choose a nail or peg that is smaller than the drilled hole, but with a wide head, so that the component can vibrate freely, but is held onto the frame.
If your xylophone is chromatic, the blocks should be arranged on the frame similar to the way they are on a piano, with the C#, D#, F#, G# and A# blocks placed back from the others in the way the black keys are set back from the white.
Finish the tuned blocks and frame with tung oil or a water-based polyurethane.