[Larry Parham]

I just removed an antenna from the bottom of my airplane and was wondering the best way to fill this 1/2 to 3/4 inch hole. For now I am using duct tape

 

[Mike S]

Try a Google search for "snap in plug buttons"

You may need to use a Unibit to enlarge the hole to fit?

Lots of choices that should work for this.

I would use some form of sealant to keep it from rattling and leaking.

 

[AAflyer]

Strong aluminum tape?aka "SpeedTape", 'cause it'll stay on in high speeds.

 

[grubbat]

Hole

Larry,
Several good suggestions already. Years ago we would utilize a "bullet" repair for holes in fuselage. Basically rivet a circular plug a tad smaller in diameter than the existing hole to a larger piece of circular alum and attach to inside of fuselage. You may be able to just use proseal to attach.
Cj

I just removed an antenna from the bottom of my airplane and was wondering the best way to fill this 1/2 to 3/4 inch hole. For now I am using duct tape

 

[Larry Parham]

Thanks for the response. The simple way for me (not being a builder) is a plug or aluminum tape.