The front door of our house has what a little searching tells me are
called "fluted pilasters" on either side. Style-wise, they look very
much like this:

http://www.homedepot.com/p/Fypon-90-...9#.UnOt8lP-2Jo

.... but mine are made of wood and are 60-odd years old and rotted at the
bottom. I could buy replacements like the one shown, or possibly more
expensive ones I have seen elsewhere. But so far those have been made of
some non-wood substance. So I have a few questions.

Firstly, I assume those non-wood substances don't rot, but I wonder
about their general toughness. When I carry luggage or my music gear
through that door, will I take a bite out of the trim if I hit it?

Second, the price of some of the pilasters I have seen so far would buy
me a plunge router. Would I be crazy to consider making the pilasters
myself? What's there now is made of several pieces; the "plinths" are
separate. When answering this question, pretend that your experience and
skills are on the "weekend-blunderer" end of the scale.

And third, should I decide to take this on, should I use pressure
treated lumber, or something else? If PT, will I endanger my health
routing it?