Sounds like you're trying to get a size-to-size fit or interference fit, which will never work. You have to leave room for air (and often glue)...
I'm lost here. Every single video I see and every TV show I watch has the pieces fit so nice and tight they have to whack them with a mallet to get them apart when they dry fit them.
Are you saying that's not the object?
Should the pieces be loose?
You have me 100% confused at this point..
"Life is what happens to you while you're busy making other plans." - John Lennon