Originally Posted by nograveconcern
Rattle stuff on the table? It should rattle the whole room.
So you need to pick some speakers first. Then an amp, and then model the enclosure w/ some software.
A DO end table would probably be easier with the drivers facing the sides than up/down. You are going to need about 6-7 cu ft net for 2 15" DVC's or HO's. More for HF's, a little less for the new Stereo Integrity 15's.
What he said
The link I sent you to Winisd Pro will allow you to model some boxes.
This should get you started on what it is and how to use it (it is free):
I was a noob too, but once I got the hang of using Winisd Pro and folks like nograveconcern helped answer my questions, things started to make sense. As nograveconcern said, you are looking at a 6-7 cu sq ft enclosure for dual opposed drivers, but if you are trying to minimize vibration, this is the way to go.
You can play around with this site to get an idea of how big a 6-7 cu ft enclosure is:
Something like a 24x24x24" box should get it done. You can go a little taller if you want the box to be more narrow but this will most likely be dictated by your sofa.
Other things to consider are material (MDF, Baltic Birch, etc). I would stick with 3/4" material for an end table and you have lots of options for the top (glass, wood, granite). Again, search around and see what other folks have done with subs as an end table.
Once you determine the dimensions, you can always take them to Home Depot and have them cut the wood to your dimensions for you from a full sheet of MDF or plywood. They will most likely charge you extra, but it may be worth it if you have not done this before. Then you need to cut the baffles for the woofers using a router and a jig. If you don't own a router you can either try and borrow one, buy one, or rent one. There is going to be some work on your part here to get this done, but in the end it will be worth the results as you simply wont get the same performance from a commerical sub without spending more money. Most likely about double.