One of the problems with FreeNAS Box v1 was that I designed it with tabs and slots to fit into each other. While it made the box easy to assemble, the slots severely weakened the structure of the box.
For FreeNAS Box v2 I avoid the tabs and slots. But I need something else in their absence to help me during construction. The answer is a fixture: Something I design along with the box that helps me build it, but not part of the end product.
Building the box will start with bonding all the major vertical pieces together. Once the cement has set hard enough for them to stand alone, the fixture pieces can be removed. The resulting assembly will then be self-supporting as the remaining pieces are attached.
The fixture pieces sit top and bottom. Pretty much where the largest horizontal pieces would eventually go, but are distinctly different from those pieces.
The top fixture has two slots for holding two of the vertical sheets of acrylic. We’ve already established such slots are bad for the structural strength of the end product, but it’s perfectly OK (and quite useful) to have them in a fixture.
Both the top and bottom fixture have round cutouts in the corners and in the mid-span T-joint so that they stay clear of any extraneous acrylic cement that might leak out. This way we avoid accidentally cementing the fixture to the product.
Each of the fixture is made of two layers of acrylic, a main layer and a secondary layer whose shapes helps keep the box pieces in place. The small round circles visible in the picture is sized for M4 screws to fasten the fixture layers together. Using screws instead of acrylic cement allows us to later disassemble the fixture and recycle the pieces as scrap acrylic in future projects.