If you think about new KIND OF PIPE like BEAUTY, ISH or BLACK... it's impossible. I have done some experiments with adding BLUE pipe basing on custom "common" resources, but list of allowed pipes is hidden for "external designers". It works probably like chapters.

EDIT: It's not true!

I tried making a new pipe called half ish for my new level but it did't get added to the list. oh well... maybe it will be possible some day, but not today.

If you want a certain pipe that gets only the right goo, then you could use the Filter option to change the goos that go in the pipe. Changing that pipe color wouldn't be that hard. King beauty balls, and changing pipe colors are some goo-d examples.

Trying to get goos to stay out of the pipe would require either that you would use a beauty, black, or ISH pipe with the filter set to (insert name of goo here), or that you create a new type of goo that would not go into the pipe when called on.

Changing the pipe color would be good in this situation.

A new pipe...hmmmm...that would require new programming (unless someone can get to it with no problemo...)

As I see it, there's no problem changing the colour of the pipe.
Just redo to the graphic files for one of the existing types.

NB: "Grey","Beauty" and "Black" all share the same corner images... so if you change those it'll change then corners on all those pipe types.
ISH has all it's own graphics.. so changes would only affect ISH pipes

Other than that you're not going to be able to specify a new "extra" type... because the "type" options are hardcoded into the game.

Looks like I spoke too soon!!

You (well.. I) can make new types of pipe!
And not just replace existing ones...
Working on a .goomod sample and some instructions now.

One small mistake made me believe that adding new pipe is impossible!
I lost a chance to be first with this innovation!

THIS IS A NEW REVOLUTION!

I added my own pipe to Experimental Level Project!
It's world's first (not smple) addin using this REVOLUTION! (It uses all revolutions in the world )