Bases for DIY sand-filled speaker stands?

Greetings to my fellow audiophiles!
I've decided to make my own speaker stands using sand-filled,
4" or 5" round, 1/4" thick, black plastic plumbing pipe.
My height preference is between 40" and 48". (Sorry, but
I believe shorter stands really reduce the overall soundstage.)
Using Monitor Audio RS-1 medium-sized bookshelf speakers.
Where can I get (or how can I build) some real quality spiked
bases, which will penetrate the thick carpet into the wood floor?
Thanks, guys!

I cut 2 pieces of 3/4" MDF for mine, shaped how you want, an glued them to make them very heavy and 1.5" tall for balance/warp prevention. Spikes are unnecessary, but can be purchased at parts express.
http://www.partsexpress.com/webpage....cabinet_spikes