Q&A for How to Make a Bottle Tree

This shouldn't be an issue. Clean bottles are facing downward so if an insect did get in and somehow didn't fly back out, if it died it would fall out usually. If not, the bottles aren't glued onto the branches so just remove the bottle, clean it and replace.

You can wash the with vinegar and water, if still dingy, use vinegar and baking soda inside the bottles to dissolve any crust.

Yes! You can put paint inside a clear wine bottle, swirl it around, and drain it. The paint will be on the inside.

We live in Idaho with deep snow and freezing cold. I've had my bottle tree out for 3 years with no problems.

It's almost impossible. It would require a very carefully crafted bottle to have the right lens properties to be able to concentrate enough sunlight. This only happens in cartoons.

Any upward angle will keep rainwater from collecting in the bottle. You can also seal the bottles and hang from from wire or string from tree branches so they sway in the wind.

Use tiny lights that are on copper wire. These can be found at craft stores and are battery operated. Just insert strands into each bottle.