My old "Frankencart" had served me well for a few years. At the time, the idea was to have a down draft top connected to the main dust collector, and a shop vac stored underneath for easy connecting to hand power tools. It was decent thinking, and execution, but I found that I really wasn't often using its capabilities. I prefer to sand in the other room while connected to my main shop vac / dust deputy setup and most of my power hand tool work happens in there too. So I had a heavy, clunky utility cart essentially.
This time around, I wanted a nimble and functional (for how I work) cart, and ended up purchasing this option from Harbor Freight to serve as the base for my idea.
My design was intentionally simple... Around the inside lip of the top tray, I secured some blocks. The MDF topper then fastens into the blocks. Easy to swap out in a few years as needed. A few inches of overhang on three sides allow for clamping to the surface. I drew inch markers along one edge of the topper for quick / rudimentary measurements and I left the cart's gear holder / handle area unobstructed which I'm already finding to be handy for holding pencils, tape measure, square etc. A scrap of plywood made a quick shelf underneath, and a coat of poly on the top (still drying in this pic) will help keep it cleaner longer. Oh, and I swapped the provided casters for nicer, dual-locking casters that I had on hand from the old cart.
cart.jpg
Part 2 of the project was to make a station that would enable me to break down sheet goods, or just generally use the track saw. Two 2x4's were prepared on the jointer and planer, and then cut so they could interlock.
rails for cart.jpg
The long rails have 3/4" dowels protruding.. these reference into corresponding holes in the MDF top.
long rails installed.jpg
And then the short rails simply drop in and are held by gravity. This creates a 6 foot long x 4 foot wide support grid where I can make my cuts - hitting the rails with a blade will not affect their utility and preserves the cart top from that sort of abuse. Other times, such as using a jig saw or drilling holes in certain situations, it can be handy to have your work piece elevated, so the rails can serve this purpose too. The grid is pretty darn flat too.
short rails installed.jpg
Certainly not a fancy solution, but I think this cart will serve me very well. When in "normal cart" mode, it's a great place to set components of my project as I move between stations - this is a long established habit for me, but a more mobile version will be more comfortable to "drive" around the shop. When in "sheet break down" mode, I can pull materials off the trailer and slide them right onto the rails and make nicely supported cuts with ease.