This car was also designed by my brother, and is quite ingenious for using set 60059 (Logging Truck) but on a train base.
The logs are floating place, as they would be resting on the bottom of the car in real life. It was quite a pain to position them into place as seen here.
The flat car is heavily inspired by the one in set 3225 (Classic Train), except this version features two bogies unlike the original set.
This water tanker is a modified set 2126 (Train Cars) design with four wheels on the two bogies instead of two wheels stuck to the frame.
Set 7597 was the original model for this boxcar, which has been made so the doors can't open.... though you can remove the handle on the side of the car and it will open fine, though the roof might not be as stable with the doors open.
This caboose was inspired by set 10014 (Caboose), but my version lacks the top part of the caboose, which is traditionally called a cupola.