App for creating .icns files

I’m trying to make Xojo a bit faster by making the icns files external. Currently my main project is 180 MB with icons and 5 MB without.

Does anyone know about an app that can create .icns files from a bunch of files? I have an older app that only uses icons up to 512x515 size. The newer apps all resize the 1024x1024 icon. But this is not good as I have some special files at 16x16 size and manually optimise the middle sized icons.

Are you looking for an icon making tool or just something to make the iconset?

If you have a bunch of images that you want to turn into an .icns with 512x512@2x then you can use Icon Composer 2x: (pre-built binaries available, just follow the link)

Thanks, Tim, the app looks like what I want.

You could also have a look at ICNSMini by Ohamaware (@Sam Rowlands )
It’s free unless you want batch processing.