To make the opening larger, i used a dremel tool. I burned through a bunch of blades cause it was the first time for me using the tool before. As long as you have a study hand you should be fine. Just don't put too much pressure on globe when trying to cut it or it might crack. I just guided the dremel tool and let it do the work. If you don't mess up on the bottom, don't worry because you will wrap the bottom with purple cloth anyway so no one should be able to see that. Not to mention it will have a coat of the mirrored spray paint as well.