I’ve been making mildly decorative but extremely useful (if not mundane) things as of late – some the things I ordered my 
for in the first place. 
One of those things was something that is just too big for any of my 3D printers: a shelf for in the shower to keep shampoo bottles and what-not off the Corian shelf, in an effort to help it dry and not retain soap residue.
The first one I made was the largest thing I have made – an 18"-long x 5.5" deep shelf using the medium acrylic. I love that I can cut big things. I put vertical supports at both end and one in the middle. While it’s working great, it has a bit too much bounce to feel that it will last with heavy Lush bottles.
So I ordered some 
Thick Clear Acrylic and made a 12"-long x 5.5" deep version, with the plan on making two for even more space than the original.
Here are some pics of the thick acrylic shelf, along with the evidence of me getting waaaay too much acrylic welding glue all over the joins. It is definitely more sturdy than the medium acrylic shelf, and should hold up fine.
Note that I do “sign” the pieces I make and use around the house – just a “W” and the two-digit year. It engraved nicely. 
I did the design in Fusion 360, exporting as DXF, importing into Inkscape for coloring inner cuts and adding text to engrave. The curve of the bottom of the side supports on this version didn’t import so I had to redraw them with less flowing smoothness of curve than the original. There is also a 1-degree slope from back to front to aid in subtle water flow. I did NOT adjust for kerf as I knew I’d be gluing it all together and didn’t care.
