OK, here is a tutorial to create new tilesets since I have been doing this a lot recently.
1) Create a new folder in the STYLES folder for lemmini. Name it whatever you want the tileset to be called.
2) Copy and paste the .ini file and the object & object mask images from another pre-made set such as marble. Change all of there names so the pre-made set name is replaced with the new set name. (e.g. marble.ini become [name of new style].ini)
3) Create the terrain images. Make sure to save them as .gif files, and for them to have a black background (NOT transparent). Make sure you don't use pure black in your terrain. They should be named in this format
[style name]_[number].gif (Just look at another style to see what I mean) Start with _0 not _1.
4) Edit the .ini file in these areas: Change the debrisColor and particleColor to hex colour codes that match with your tileset. Also set it so the tiles = value is equal to the number of terrain peices in your new set. You can also set the bgColor to anything if you want rather than dark blue.
5) Now for the weird bit. You need to open the terrain files in a software called IRFANVIEW which can be downloaded for free from the internet. Then you need to resave them as a .gif but with these options (you can access them by clicking the options button at the bottom of the save window) DON'T do this for terrain peices with no transparent space, such as steel peices!
If there is other software that can save gifs like that you can use that
6) Now you need to edit LemmixStyles.ini which should be located in the same folder as lemmix. Scroll down until you reach the text with names such as [Lemmini_1]. Just copy and paste the last one of these to underneath it and change it so it looks like this:
[Lemmini_1]
GraphicSetClass=TLemminiGraphicSet
BrickColor=0
GraphicSetArchive=
GraphicSetId=[One more than the last lemmini style's]
GraphicSetIdExt=0
GraphicSetName=[Tileset name]
GraphicSetPath=Styles\[Tileset name]\ I think you need to have the lemmini styles folder in the same one as your lemmix folder as well as in the lemmini source files for this to work.
If you follow those steps you should get a tileset, though the objects will not have changed. Editing objects is quite difficult, but the size of each frame is calculated as Image height divded by number of frames. You may be able to work out the rest from there.
Attached is the bubble tileset with those steel peices in as well, just replace the bubble folder with it:
