So... I'm making a first birthday cake and smash cakes for twin girls turning one. I'm hesitant to make the smash cakes with fondant (black fondant at that!) but the mother is insisting.

My real issue though is the mouse ears. I have plans to make the "caps" with the half wilton sports ball bans. I want to make (fondant with added tylose) ears (ahead of time so they can dry) to attach to the caps. My question is what size circles should I use for the ears? I don't think I have cutters that will be as big as I'll need so I'll have to improvise.

AND How should I attach the finished/dried ears. I have a plan to cut slits in the fondant covered cap cakes and wedge them in, adding edible glue- but I fear that may look messy and I want a clean seam. I don't want them to flop around. Neat, clean and structurally sound is my goal. HELP!!!!

I, too, would like to know how to apply the ears.  I'll be making a Minnie Mouse birthday cake for my niece's 2-year old daughter and will be making the ears.  Was trying to figure out how to do this as well.

I made a Fantasia cake for my son's 4th birthday. I used a small bowl to cut out gumpaste circles for the ears, cut a sliver off each side so they would sit flat and inserted skewers into the flat edges and let them dry hard (give them at least a few days.) When you assemble the cake, just pop them in and use a little royal or melted chocolate to give additional stability. Sorry, this was before I started taking very good pictures, but you get the idea :) 

  
I made this cake last year.  I rolled out black gumpaste 1/4" thick.  used a round tupperwear contained for the size of the circles to cut it out.  I inserted three toothpicks into the bottom of each ear.  I let them dry in wilton foarming cups for a week to harden.  The ears were big and heavy and unfortunately needed that extra support.  However I do not like using any none edible objects in my cakes.  But sometimes decorations need a little help.  My ears stood up wonderfully and I didn't have any issues.

I cut a flat edge on the bottom of the ears, attach them with almond bark (building up some almond bark behind the ear at the base to support them from the back) then use a paintbrush and some gel color and paint the almond bark black. It's almost undetectable.