ESRICH 6 Pack Wood Panels with 4"x4", 5"x5", 6"x6", Square Craft Wood Canvas Boards, Blank Unfinished Wooden Art Board for DIY Art Creations Such as Painting, Acrylic Pouring, Resin, Burning, Collage

putting some hides under the bedding can be good for hammies! mine doesn't really use them at all, but it can't hurt. also for the bedding, ripping up toilet paper or even shredded paper can be used in a pinch. it is still preferable to use store bought paper (unscented!) bedding, but using a diy method is better than not having enough bedding. cardboard for sand might be iffy? the sand might leak out. hammies also use sand baths to pee in a lot so idk if the cardboard would get yucky, but if it's only temporary before you get a better dish than it probably would be okay, just monitor it. platforms are super helpful for putting down the water bowl and wheel and sand bath. unfortunately, they are stupid expensive - like $16 just for one! what i did for platforms was glue a wooden dowels (20 pc for $7) to wooden canvases (MUST BE UNTREATED/NONTOXIC) ($10) and was able to make a bunch for super duper cheap. this way you can add the wheel, water bowls, more hides, sand bath etc without the risk of crushing you hamster. (edit): i used hot glue to glue to wooden dowels to canvas. hot glue is not safe for a hamster to chew on, but i monitor mine and so far he has had absolutely no interest in chewing it.