The sound of your instrument is based a lot on what materials you use. If you’re looking for a particular tone of instrument then it’s important to consider what materials will be vibrating in order to make audible noises.
A tin will sound tin-y, a wooden box will sound softer, a wooden box made of a different type of wood will sound different too. Pretty much anything you use for your sound box will have its own unique sound and tone, and if you’re building things DIY you might not always have a lot of control over the exact material you’d like.
One important thing to consider, is that when you add strings to anything, then you add tension to those strings to tune them, the strings will pull the two anchor points together and can be surprisingly strong. Soft wood and thin metal WILL bend when you add tensioned strings. They will put a lot of pressure on the weakest point between the two anchors and will break your instrument in half if you’re unlucky!