You're probably thinking of Mark Lords docking stations (at least for the wooden ones). Click the "Home Docks" link at the top of the page.

That one has only been made (currently no longer produced) for the MKII(a), which has a different connector/sled compared to the MkI (which you, according to your signature, have).

A number of users have produced one-offs in various materials.

I think your best bet is finding someone local that is handy (unless you meet that criteria yourself ) that can put together a box, in whatever material you favor, that houses the MkI docking sled you have (and, as you say it'll stay in the house, don't need in order to mount it in the car). That makes the whole project fairly easy - or you can get the fitting connector
and build something like Marks docking station, but that fits the MkI. Info on where to find them, as well as pin-out can be found here

/Michael