If you are trying to go on the cheap and use random things around the house to support your piano, you’d better be careful.
What do most people have laying around the house that would be a candidate for a piano stand?
Should I just use a table? Sure, you could use a coffee table. Most coffee tables are very low though. Not many are long enough to support the full length of a digital piano though. Depending on your actual coffee table, it could not be very sturdy. If it has glass on the center, your table may not even be completely level. This could put excess pressure on the glass–a disaster waiting to happen.
How about a regular desk? Desks are usually extremely high to put a piano on it. You may be able to get away with putting very thin keyboards on a desk to practice at home. It will take up a ton of space, and you will need to clear off your desk every time you use it. Digital pianos will dominate the entire desk, almost requiring the entire surface. You may as well dedicate something that works as a better piano stand!
If you have textbooks or heavy phone books laying around, they are an option. All those books you couldn’t sell back in college are sitting around collecting dust, so why not try to find a use for them, right? They may weigh a ton, but they are definitely not sturdy! Get into some emotional lines of music, get carried away, and your books could tumble or your piano could very well slide off and crash. What a waste! Bad idea unless all you have is a piano and books in your studio apartment scrounging coins for your next ramen meal.
Unused chars is another option. This can be stable, but chairs are rarely flat all the way across. Heavy pianos can have unnecessary pressure on the wrong points. This can cause bending or stress on the expensive piano of yours! Also the chairs get in the way of using a pedal below since your feet are blocked off. My advice is to not have any makeshift piano stands at all!