i think making a pipe would be harder than making a bong would.

i dunno what you would be able to call the pipe and thats the main problem.

you could always call the bong a vase like stated above..

i made a "vase" one time in ceramics and mr. spencer my teacher brought it out and was like.. what is this? i said it was a vase. he said he wasnt stupid and gave it back to me... thing was badass too, i put alot of time and effort into that bong.