Tribes allows you to replace the skins on every object with those of your very own. This tutorial will show you how to extract a skin from Tribes, and then convert your skins so that they will work with Tribes.

Step 1
The first thing you need to do is download a few tools that you will need. You can download them here:
Tribes Tools
Skin Tools

Step 2 - Extracting your skin from Tribes
All of the skins for Tribes are in .vol files in your Tribes\Base folder.  In order to extract the files from the .vol files, you need to use Tribes Tools.  This program will also convert the .bmp files to an editable format.  Launch Tribes Tools and click on Tools and then click on VOL File Extractor.
In the upper left column, go to your Tribes\Base folder.  In the lower left column, select Entities.vol.  In the middle column, select plasma.bmp.  In the right column, select the location that you want your file extracted to.  In the lower right corner, put a check next to PBMP -> BMP.  Then click START.  A progress bar should come up and then go away, and now your file should be where you told it to be extracted.

This is what your screen should look like:

If you don't need to extract the skin from a .vol file you can just click Tools and click PBMP -> BMP and use that window to convert your skin to an editable format.

Step 3 - Editing in PhotoShop
Now open plasma.bmp in PhotoShop.  In order to edit the image, you will need to click Image, then go to Mode, and click on RGB Mode.  Next you need to duplicate the layer (Ctrl + J), and then delete the original layer.  You can now modify the image.

Step 4 - Saving in PhotoShop
After your image is edited you will need to go to Image, then go to Mode, and put it back on Indexed Color.
A prompt will come up.  Click the drop down next to Palette and click Custom.

Another prompt will come up, and you need to click on Load, and go to where you extracted Skin Tools and choose pal3PS.act and click Load.

Click OK until you get back to your image.  Now click File, and click Save As.
Save your image as a .bmp file.
A prompt will come up, and you need to make sure that Depth is on 8 Bit.

Step 5 - Converting to PBMP
Go to where you extracted Skin Tools and right click on makeskin.bat.
Delete everything after @echo off
After @echo off you need to add the following line:
    makeskin pal3 your_image_name.bmp plasma.bmp

Replace the text that says your_image_name with the name of your image.  For example, I named my new skin: plasmaskin.bmp, so my makeskin.bat will look like this:
@echo off
makeskin pal3 plasmaskin.bmp plasma.bmp

plasma.bmp is the file that will be created.

Save your file, and then run MakeSkin.exe

It will create plasma.bmp and put it in the folder that MakeSkin.exe is in.

Step 6 - Final Step
Now move newly created plasma.bmp from to your Tribes\Base folder, and launch Tribes.  It will now be on your Plasma gun.

Step 7 - Armor Skins
If you're making armor skins, there's an extra part that you add to your makeskin.bat:

@echo off

makeskin pal3 light_armor_skins.bmp skinname.larmor.bmp
makeskin pal3 medium_armor_skins.bmp skinname.marmor.bmp
makeskin pal3 heavy_armor_skins.bmp skinname.harmor.bmp
makeskin pal3 female_light_skins.bmp skinname.lfemale.bmp
makeskin pal3 female_medium_skins.bmp skinname.mfemale.bmp

vt -sp MySkins.vol skinname.larmor.bmp
vt -sp MySkins.vol skinname.marmor.bmp
vt -sp MySkins.vol skinname.harmor.bmp
vt -sp MySkins.vol skinname.lfemale.bmp
vt -sp MySkins.vol skinname.mfemale.bmp

vt MySkins.vol

The left .bmp file is the input, so put there whatever you named your file, and the right .bmp file is the output, you can replace skinname with the name of your amor.

What this does:
Converts the .bmp files to the Tribes .pbmp format.
Then puts the converted .bmp files into a .vol file called MySkins.vol, which can be renamed to whatever you want.
Put the .vol file in your Tribes\Base\Skins folder.