What do you do if you have the perfect spot for a matrix, and you know the resolution you want, but this leads to a pixel spacing (say 1.25″ or 1.4″) that is not widely available?
“White hristma”
In my first year, I decided I wanted to put a matrix over the upstairs double-wide window on the front of the house. At 2″ spacing, it made sense to have the matrix be 32×24.
That worked. However, I later found out that I really like Superstar matrix sequences, which are generally 50×24. So, the 24 rows turned out to be a serendipitous choice, but a width of 32 pixels is not enough. Scaling looked wrong (these sequences have a retro, blocky look), but not scaling causes the edges to be cut off:

Custom Matrix From HolidayCoro
This year I found out that, if you email them, HolidayCoro will make HDPE with pixel holes in any spacing you want. The finished sheets are almost 8′ square, which is bigger than most “off the shelf” matrix nets from other vendors.
For my window, and some other purposes, 1.4″ spaced and 1.25″ spaced matrix seemed like the way to go, so I ordered 2 sheets of each.
Results
The material arrived quickly, as their products usually do.

The bullet pixels I used (theirs, which have a 3″ spacing that needs a little less power and is a smidge lighter than 4″) fit properly, so assembly was relatively easy.

The end result was also what I expected:

Final Thoughts
This was a simple project that fixes a minor thing about my display that was really bugging me (maybe you know the feeling?).
Per square foot, this worked out to be the same price vendors typically charge for standard 1″ or 2″ spacing (or maybe even a little cheaper), so if you think a custom spacing would be useful, I wouldn’t hesitate to inquire.