Narrative with PICS...
Doesn't seem hard.
Oh, it's not. If you aren't worried about tracking smooth, accuracy, and the like. If you have good glue, not old, and aren't gimpy and in pain.

Old and forgetful. All this will make sense as we take this trek. Mistakes, (learning opportunities,) were created.
After watching dozens of videos on this project, I decided to go with 3/4 ply since I (a) had some on hand, and (b) wanted the extra weight for stability and because most of the stuff I was going to cut on the sled would have weight itself. 3/4's it is... The first step was to decide on the size. I knew I wanted to be able to cut stock at least 24" across, anything wider I'd use the skill saw and special jigs I'd bought. I figured I'd make the sled the width of the table. Full support of the off cut and the primary.
First step was cutting the 1/2 sheet of ply and I knew I needed the 24" wide piece, two 4" wide pieces for the front fence and two 5" wide pieces for the back fence. I cut them at 24-1/4 and added 1/4 inch to the other 4 pieces as well. That way a cleanup pass against the fence later would still leave the full size I wanted with the 1/8" blade. The Rails would be 1-1/2 inch thick per the recommendations in the various videos and the first step in the process was to glue those up. It used every carpenters clamp in the shop. ALL of them.

- 01 rail glue up.jpg (134.99 KiB) Viewed 4530 times

- 02 glue up view 2.jpg (179.23 KiB) Viewed 4530 times
While the rail glue up dried, I went to work on the runners. They were going to be made from maple, as all the videos recommended hardwood or any of the plastics. They recommended staying away from the softwoods or plywood as they would wear quickly and all your work would soon result in a sled that had side to side movement, allowing variation in the cuts. I cut the rails to fit snugly but run smoothly. The videos recommended placing the rails in the slots on the table on top of pennies or washers to raise them slightly, with a few drops of super glue on them to properly align them, with them bottom of your sled squared to the fence. Weight the bottom on the table and let it sit. When you remove it, you can attach the two rails with a screw at each end then check for tight fit but smooth movement.

- 03 sticking the rails.jpg (176.8 KiB) Viewed 4530 times
This was the worst part of the entire build. First my superglue was about a year old, and failed to hold on the wood. Every time I pulled the bottom of the sled up, one rail or the other would pop loose. I finally gave up and used Titebond. Then carefully, before lifting, slid the sled backward and clamped the back end of the sled rails to the bottom. I then tilted the sled bottom up, fully supporting both rails and then clamping the front end of the rails to the bottom.

- 04 screw em on.jpg (160.34 KiB) Viewed 4530 times
I transferred the inverted bottom of the sled to the workbench and put a screw at each end and then put it back on the saw and tried to slide it back and forth, and found it binding. I used the rabbit plane to trim the runners until the rails slid smoothly but still held the sled tightly. HOURS spent attaching the rails. Gee, in the video this was a fifteen minute evolution.
Next up, was attaching the front rail and I got set to check for critical alignment. Then I remembered the front rail is there only for stability and to keep the bottom from separating. I spread glue, and clamped the rail across the front aligning it with the front edge of the sled and left it to dry overnight.

- 05 front rail.jpg (182.64 KiB) Viewed 4530 times
The next morning, I came back out and inverted the sled once again and zig zagged screws about every three inches down both edges, staying away from the middle glue line on the lamination. I also did NOT put any screws in the middle section of the rail between the runners at this time, since we DON'T know the exact location of the saw kerf.
Now for the most critical part of the entire build, the installation of the back rail. Many aligned the back rail using the fence as a guide, but the critical relationship in my opinion here is the rail and the blade. I ran the saw kerf three quarters down the sled bottom and used a framing square to align the back rail to the best of my ability with old eyes, and clamped it in place.

- 06 alignment of the back rail.jpg (115.03 KiB) Viewed 4530 times

- 07 position the back rail.jpg (144.33 KiB) Viewed 4530 times
I had predrilled the holes prior to installing the rail, so I put ONE nail in each end, then reinstalled the rail on the saw, and made the necessary five cuts for the five cut test to check for the accuracy of my alignment. (Four edge cuts on a square of luane, then a 2" strip cut off one side.) I then measured each end of the strip to check the accuracy of the cut. If there is a difference, you divide the difference by two and correct the error on the necessary end of the fence. MY strip of 2" luane measured 2.01 inches and 2.06 inches. I was off .05 inches for an error of .025 inches. I decided that for woodworking two hundreds of an inch error was well within MY range of acceptability.
I removed the sled, re-inverted it on the workbench and installed the rest of the screws in the pre-drilled holes, and then drilled the holes on either side of the kerf in the center section between the rails for the front and back rails and placed screws in those. All were countersunk and insured they were just below the surface so they didn't mar the surface of the saw table. I now had a working sled.

- 08 working sled.jpg (110.41 KiB) Viewed 4530 times
Time to install the rail for the stop block. I had some track normally used on the kayaks, made by YakAttack. Great product.

- 09 rail track for stop block.jpg (129.93 KiB) Viewed 4530 times
My plan was to use the old stop block off the miter for the table saw that I had removed and tossed as it got in the way on the miter. I had tested it and it worked in theory. I installed the track on the face of the rail even with the top edge. Testing the stop block, it would work with wide boards but nothing 1" or less. Fail...

Hmmm? Maybe if I trim it.

- 10 Stop block fail.jpg (125.44 KiB) Viewed 4530 times
So I trimmed off the foot of the back edge of the stop block then polished off the roughness. If it worked well I would use the 220, 320, and 400 grit to make is shine. Nope, still didn't work at all.

- 11 adapt and overcome.jpg (125.33 KiB) Viewed 4530 times

- 12 polish and smooth.jpg (131.22 KiB) Viewed 4530 times
A puzzle since it worked so well before. Late that evening, sitting watching Justified on Prime, it hit me. I had placed the track on TOP of the rail... Idjit.
Little things you forget come back to haunt you. Not that much fun.

Meh, I'll just make a custom stop block that LOOKS good and works better.
So, I dug around in the scrap bin and found some leftovers from the cutting board builds, and started playing with them. Yup, this will work.

- 13 next steps.jpg (130.83 KiB) Viewed 4530 times
I took two walnut 1" pieces and cut rabbits in them, and fitted them over the rail and cut them to reach the bottom of the sled. They will ride the rail on each side of the aluminum assembly.

- 14 rabbits cut.jpg (137 KiB) Viewed 4530 times
I cut the maple and walnut laminate pieces to width, and laminated them together. They will go between the walnut legs and rest against the back rail when the stop block is in use and put some strength in the stop block, plus look cool as all get out. When the glue dries, I can think about assembly.

- 15 laminated and waiting.jpg (190.27 KiB) Viewed 4530 times
More to come, but the sled can be used as is.....