[Lilafernim]

Sounds good if you can increase the size eventually. I know this sounds weird but I made a full setup for my current hamster in a slightly too small cage so when transferring I had the then replace and rearrange a lot of things. If you can I’d prioritise increasing the cage size then focus on its contents and rearranging to be adjusted to the correct size enclosure. It would’ve made my life easier instead of buying smaller house, then getting a bigger one, same with wheel and other bits.

As mentioned by Ria you can pick up a secondhand cage as well for cheap. I thought of diy myself before getting my cage but realised it would end up costing the same as buying a brand new cage. Mine is an Alaska and cost £20 from Facebook.

Also if you have any cork material I guess you could use that for the wheel or cardboard but I would definitely not leave exposed glue on it as hot glue guns have toxic glue. I use toxic free pva glue for any hamster crafts it’s just as cheap, if not maybe even cheaper. I don’t know if the gap could be fixed with pva on its own, that’s why I mention cork or cardboard but might struggle to spin or clean. A cheap solution could be to get a second hand wheel, I like Trixie wheels and you can pick them up for around £10. Mine is 28cm and think it was £11 on amazon. If you got a 21cm one they’re less than £10 and second hand you could pick one up for £3-£5.