Sure, I have a couple of DIY items that don't require a huge amount of skill.
Hiking pants with zip-off legs have become very popular. Did you ever weigh a pair? Those separating zippers have to be pretty strong and weigh a lot. Also, I find it inconvenient to stop, take off my pack to dig out/store the legs, take off my shoes to put the legs on and off, etc. So, my preference is to find nylon pants with wide enough legs to allow me to roll/fold them up to around the knee somewhere. A pair of grosgrain ribbons can easily hold up the legs. I did sew a button hole on the end of two pieces of ribbon, then sewed the ribbons to the each outside seam at spots that I liked along the thigh. The ribbon is inside and a button is stitched through the seam and ribbon to the outside of each leg. When I want to shorten my pants, I just fold them up and button the ribbons in place. If I had no way to use a machine, I could hand-work the button hole, or come up with another method to fasten it, or just use two cords on each side, tied. I don't see why a cord run through a fold on the loose end of the ribbon could not "button" the pant legs in the up position.
Another simple DIY item is a cozy for a water bottle, food container, etc. In winter, I carry a Gatorade bottle wrapped with windshield reflector material. I've stopped drinking hot beverages from it, in case any nasty stuff is thrown off by the plastic, but I do use it for cold drinks stored a short time, and a hot water bottle is marvelous in the bottom of a sleeping bag after a day of hiking in cold rain... The same windshiled reflector and tape covers a Ziplock bowl that I set my food baggie into while it rehydrates. I could cozy my pot, but I usually cover my bowl, instead.
Cut the walls from a couple of soda cans, and staple them together for a cheap windscreen that holds up longer than aluminum foil.
It is a start!