Loudspeaker Designs and Articles for the DIY Enthusiast
Invictus: (adj.) Incapable of being conquered, overcome, or subdued. Invincible.
Synonyms: unbeatable, unconquerable,  invulnerable, unshakable, indomitable,
impregnable, unassailable, insuperable, indestructible, supreme, insurmountable,
Invictus Sealed enclosures

The Invictus is offered in two different sealed enclosures: A tall,
slim floor stander, and a rather stout looking bookshelf. For
most, I'd recommend the tower version as you need a stand
anyway, and this one comes built right in. But recognising that
some situations would be better suited with a bookshelf, we have
that iteration drawn up below as well. The sealed version gives
surprisingly little away and still provides excellent bass when
supported by the room, but won't shake with walls with sub 40 Hz
material. If you plan to augment with a sub, one of these may be
the optimum iteration for you.
Sealed Tower:

The sides are small enough that I deemed the ladder brace
unnecessary, but certainly it could be added, or a couple of
horizontal window pane braces could be added should you
choose. 3/4" MDF is suggested for the enclosure construction.
Tips and tricks:

While I did not do so, certainly it would not be unreasonable to
add a couple of broomstick braces from the center of the two
front braces to the rear panel, although the 'knuckle rap test' did
not indicate any signs of undue enclosure resonance. the
finished cab will likely have a solid wood front baffle for a total
baffle thickness of 1.5".
I did not design a near wall version of the Invictus, and
suggested placement is to have their front baffles between 2 and
3 feet from the front wall. This doesn't mean they can't be placed
closer. The sealed versions will be more tolerant of near wall
placement than the MLTL, although the bass in the MLTL
doesn't sound too out of proportion. Certainly stuffing the ports
with foam is an alternate solution, and provides more design
placement flexibility.
Links to:

Main / Design Goals

Driver Selection

Sealed tower Cabinet construction
Sealed Bookshelf cabinet construction
MLTL Cabinet Construction

Crossover Design

More Measurements

Listening Impressions
A two way design using
top shelf drivers
3 different enclosure variations
Closeup showing scalloping the rear of
the woofer cutout to ameliorate
potential cavity resonances.