here a guy has adapted a Torus script by Jace
maybe it's cheating :)
so from a torus script with this parameters an heptagon can be created :)

# The next five parameters define properties of the torus to be created
# Note: CS is an abbreviation for Cross Section
CS_VertCount = 3
segmentCount = 7
CS_Radius = 2.0
torusRadius = 4.0
numTwists = 0

My try :)
Ps In TopMod, call the Py Console, load the script, modify the parameters as above, Ctrl + Enter, launch the script
et voilà :)