We made our day bed out of pallets so it was really easy and just jazzed it up with cushions/pillows. If you can find pallets in good condition it’s really simple and doesn’t require any special tools – just screws, drill, sander etc

I would look at getting one that can be assembled easily.

We have our eye on a easy to assemble day bed.

There are plenty of instructions on Pinterest and the internet especially with pallets.