I once had a homemade set that came with my formerly owned
P18-2.

It had a galvanized steel pipe for an axle.
It had standard wheelbarrow wheels; the bearings where taken out and the axle fit thru the hubs. NO bearings, just rubbed on the pipes. Held in place by hose clamps around the axle.

Did they work? Why yes they did.
Did it rust some? Why yes they did.
Where they as good as Trax? Why no.
They had some trouble in the loose sand, but they did work, and I used them fot years.

And fot craddles?
Jig saw cut pieces of PVC pipe, contact cement some carpet on them, viola!

My last boat a owned, a N6.0, came with Trax.