Due to using ScummVM and not having the original disc images, the GOG (and presumably Steam) versions of Toonstruck are missing the original icon (intended to be used with a PIF shortcut). I have provided it here, along with versions that add a transparency effect to make the icon look cleaner (although I had to shift everything left one pixel to make an effective border). The Steam version of the icon also is lacking a 256x256 version, so I created one using waifu2x-caffe.
TOONSTRK.ICO is the original icon, with a solid black background.
TNSTRK95.ICO removes the background while using a solid black line to accentuate details. It should be in a format compatible with Windows 95 (it's also compatible with Windows 3.1, but you really shouldn't be playing it that way).
Toonstruck original with transparency.ICO is the same as TNSTRK95.ICO, except it is integer-upscaled to 256x256 (with several intermediate versions).
Toonstruck Steam +256.ico is the icon used by Steam, with the addition of a 256x256 version (cutesy of waifu2x-caffe).