snota

You know what's going to threaten way more birds than all those things put together? Climate change.

I agree that outdoor cats should be banned as well.

I think everyone has answered your question correctly so far. You can't beat plywood for strength, but it is expensive. There are middle ground alternatives.

There is Medium Density Fibreboard (MDF) which is between the two on strength but takes paint brilliantly. Many cabinet makers use this exclusively for mid range quality furniture.

Even cheaper is chipboard which is about as bad, or worse than OSB but you can get it laminated. Most very cheap furniture from places like IKEA use it and it can do a reasonable job.

All of these materials have their quirks, mainly on how you finish end grain (even plywood). Both MDF and chipboard suck at taking a screw so you have to get special screws and use them carefully. Make sure you do some research, there's plenty of YouTube videos on using the products.

It's a tough one. When we found a greenfinch with trichomonas it was heart breaking. We tried to treat it but it was too late. At the time we researched it and the RSPB advised to clean and move feeders regularly. Perhaps that's not good enough.

I honestly think this is the worst use case for a 3d printer. The part isn't improved by printing. You can buy the part easily. The cost of modelling time and printing is more than the replacement. There's a decent chance the replacement part would have arrived quicker than the print took.... Sorry to be a bore, it's better than an octopus or another benchy, I'll give you that.