Samson subwoofer
Gattiweb
Construction
25mm MDF is a little hard to source, but I found a local supplier who also will cut to size. Off to a quick start then ... 
My Jasper jig made quick work of the driver cutout. PVA glue and screws hold everything together, although it's a little difficult to stop things 
shifting slightly while inserting the screws. Next time I might invest in some more clamps to avoid having to use screws.
For added rigidity I epoxied the MDF shelf brace into place.
To increase strength, improve coupling between panels and guarantee an airtight seal, hardwood battens are glued into all seams.
After gluing the back into place, it's time to smooth things out. Ah, the joy of power tools, working night & day to finish before Christmas 2005.
Here I've glued and nailed the base into place.
After filling the gaps and sanding, they're finally ready to paint.
2 coats of sealer primer
Satin black enamel top coats (sprayed on) Cabling and polyester stuffing
Building the Marchand kits Fitting crossover into MDF box
Completed Dec 23, 2005 - thanks Santa :)

Measurements

The final lowpass filter configuration was finally settled on at 6dB gain, with a 2nd order Butterworth lowpass fc at 40Hz.
Here's my nearfield measuring setup using a calibrated Panasonic mike & Bamberg Lab pre-amp.
And here's the JUSTMLS measurements of the driver alone, and then with the lowpass filter in circuit.
Above shows a very close match to the Peerless XXLS 830843 spec sheet. With the filter in place, there's a nice 12dB/octave rolloff above 40Hz.
Finally I measured the total combined output of Samson & Delta.
The measurement below was taken using an analogue (corrected) Tandy (Radioshack) SPL meter at the listening position. 
The hump at 57Hz & dip at 70Hz are room modes.
March 2006
Time to build the grills & I've also decided to repaint Samson in off-white to help it blend into the decor.
Pine frame Primed & installed grill clips
Primed & grill mounting holes drilled Finished in satin pearl enamel (sprayed)
Grill cloth installed into frame
Completed April 30th 2006.
Oct 2006 - I changed the grills to a beige cloth.
The active lowpass filter has also been upgraded and now includes a VU meter. Full details here.
home design active filter / VU meter