Typically, for amputees, the illusion works with a two-sided mirror set up vertically on a table. Placing the arms on either side of the mirror, in the same position, and moving them tricks the brain ...

You can get new moving boxes for around $1 to $3 per box at The Home Depot, Lowe's or U-Haul, but free moving boxes are also readily available through sites like Craigslist, Facebook Marketplace ...