18650 8x5 cell holder w/ bolt tabs to secure

This is an 8x5 18650 cell holder as you can see in the STL picture. I used ST8 to design this holder in an attempt to make a better holder than the current ones on the market. I plan to use 21 blocks of 40 cells (84S10P) to install in my Ford Fusion Energi to more than double my current EV range. If anyone has any suggestions on what I can do to make the holder better, please let me know in the comments below. Thanks!