So I am making this cake for a friend later this month but I am not sure what sizes to use. Its up to me so the servings amoun doesn't really matter. I am not sure what sizes I should make the cake and gumball machine so they look decent any help is greatly appreciated. Thanks!!!

http://images.search.yahoo.com/images/view?back=http%3A%2F%2Fsearch.yahoo.com%2Ftablet%2Fs%3Fei%3DUTF-8%26p%3Dgumball%2Bmachine%2Bcake&w=106&h=160&imgurl=www.bing.com%2Fimages%2Fsearch%3Fq%3Dgumball%2Bmachine%2Bcake%23focal%3D53b687d87cc53e84f1c4065ae18b5cac%26furl%3Dhttp%253a%252f%252ffarm3.staticflickr.com%252f2721%252f4277780099_3f346d8c96_z.jpg&size=&name=search&rcurl=http%3A%2F%2Fwww.bing.com%2Fimages%2Fsearch%3Fq%3Dgumball%2Bmachine%2Bcake%23focal%3D53b687d87cc53e84f1c4065ae18b5cac%26furl%3Dhttp%253a%252f%252ffarm3.staticflickr.com%252f2721%252f4277780099_3f346d8c96_z.jpg&rurl=http%3A%2F%2Fwww.bing.com%2Fimages%2Fsearch%3Fq%3Dgumball%2Bmachine%2Bcake%23focal%3D53b687d87cc53e84f1c4065ae18b5cac%26furl%3Dhttp%253a%252f%252ffarm3.staticflickr.com%252f2721%252f4277780099_3f346d8c96_z.jpg&p=gumball+machine+cake&type=&no=3&tt=115&oid=http%3A%2F%2Fts2.mm.bing.net%2Fimages%2Fthumbnail.aspx%3Fq%3D4599120335406233%26id%3Da5e709049aa37e598853dd5a6ebd900e&tit=Janina%26%2339%3Bs+Gumball+Machine+Cake+%7C+Flickr+-+Photo+Sharing%21&sigr=15d4r33h7&sigi=1565mcgqf&sigb=120n3k9ag&fr=ipad

I have no idea how many people the cake is for so,

If I were doing that cake, the first thing I would do is get my glass fish bowl.
If it's a 5" round glass globe, then use a 10" bottom cake.

Looks like the bottom cake is twice as wide as the glass bowl.

Of course if you know anyone who has a gumball machine, you could even make a quick mold of the silver (coin area) part. That makes it really nice to create your details easily, and may dictate your size.