I need your advice!!!! please help!!!!?

E6000 glue is good and wood is the sturdiest background I think; that many bottle caps will end up heavy. If you have some caps you won't be using, try gluing them on a piece of scrap wood to see if they hold. Hot glue is a temporary fix, sometimes may hold, but can be picked off. This is from trial and error on my own projects. Check out your local Walmart, who has lots of glues in 2 areas, art supplies and hardware, read labels to see if metal to wood holds, then the trial and error begins. Give the trials a bit of time to dry then try to pluck the caps off... Also, you might go in search online of other artists who've used this type of medium (metal on wood) and get some ideas from them. Sounds like a really neat project. A local artist here did some portrait art with pennies and got a lot of news coverage from it.