Yes, they clear weeds, for sure. And considering what a PITA it will be to clear weeds without one, it's well worth the effort to make one.
Check out page 1 of my aluma-jet build. Toward the bottom you will see some pics showing how I built my stomp grate.
You can make the tines out of 3/4" x 1/4" stainless flat bar. That's better than the brittle cast aluminum ones that are typically found on intake grates. You won't break stainless, no matter what you hit.
To make the tines, cut them a little bit longer than the intake opening, long enough for the back end to overlap the lead edge of your intake plate. Use a grinder, and grind a 'step' on the end of each one. This will allow them to fold up against the intake plate edge, and keeps them from being able to flip up into the intake if you bump across a log, rock, etc.
For best water flow dynamics, sharpen the bottom edge of the tines like a knife edge, and on the top edge, grind to a radius. A belt grinder makes quick work of this. If you don't have one, use an angle grinder with a coarse flap wheel, it will do a nice job of removing material quickly without overheating and pulling the temper from the material.
Next, cross drill through the tines on the forward end for a bolt which will act as your pivot. Drill another hole through all of them, a few inches back from where you drilled the other holes. Through here, use another bolt, with a nut on each side of each tine. This will lock them all together, and keep them correctly spaced.
Then, where the front end of your intake grate bolts to the pump intake, you will need to modify this block of aluminum by having a set of lugs welded on each side, and one in the center. Cross drill these lugs for your pivot bolt.
Next you'll need a tele flex cc633 series push-pull cable, with 4" of travel. You'll also need the other items shown in page 1 of my build, such as the rubber grommet, and locking collars, and the 3/4" NPT cap with a center hole drilled for the cable to pass through.
Hope this info helps! The pics of the grate on my build is the older configuration. It doesn't have the step cut into the tines. I can take pics of my newer, improved grate... let me know.