Works best with same size images (with transparency or not).
Smaller images will be centered.

To generate a fading spray enable mipmaps, load a main picture,
and then choose another picture under a mipmap of choice.

To generate an animated spray select multiple images in the file browser.
The frames are displayed in the same order as they appear in the file browser,
and each one lasts for 0.2s. Animated gifs and videos are also supported.

To download final spray click "Save as VTF".

Transparency is broken in Linux version of TF2 when using DXT1. Use DXT5 instead!
Auto 1024 768 720 512 256 128 64 32 16 8 4 Custom x Auto 1024 768 720 512 256 128 64 32 16 8 4 Custom
Generate Mipmaps
Scale to fit
Use single image for animation

Image Encode settings:

Texture format: RGBA8888 RGB888 RGB565 BGRA5551 BGRA4444 DXT1 (One bit alpha) DXT5
Sampling Method: Default Point (Pixel art) Trilinear Anisotropic

Filename:

Convert   Save as VTF   Save VMT

Preview:

Video import settings

Start frame:
End frame:
Playback speed: Import all frames
Import
You might need to disable hardware acceleration if import fails, or to improve performance