There are dozens of different ways to mount of pull up bar. It's a project that's really unique to your situation so there's no way to give a design that everyone can use. That's why I haven't done a project for it yet even though it's a very important piece of lifting equipment. But I finally decided to just shoot a quick video showing you what I did to install a pull up bar in my home gym.
The most well known commercial neck harness costs around $40. For what amounts to a few straps and carabiners that's quite a lot. I decided to try to make my own. I did it for less than $10. I use it mostly for strengthening the muscles to reinforce proper posture. There is another DIY design out there but I decided to try to make mine look a little more professional.
Lifting platforms are cool. But they take up a lot of space, they can't really be moved or stored, they weigh hundreds of lbs., can potentially cost over a hundred dollars, and they require a truck or trailer to get the rather large materials home. I came up with a smaller, lighter, cheaper, and portable solution. Though it is designed specifically with deadlifts in mind, that is all I need it for. And it only cost me $15.
Another project that I made from scrap materials. It's a glorified shelf / coat rack but I made it to store my weight lifting belts and other small gear. I previously had these lying on the floor so this storage solution is an improvement.
I have wanted to do some sandbag training for a while now. My goal was to use things around the house in order to make these completely free. Lest I get some complaints, I know it's not best sandbag option out there. I'm not saying it's good for any purpose you might want to use a sandbag. I'm just showing you what I did to make some basic heavy bags for free. These weigh 50 lbs. each. I've had them for a month now and they have been working well for my purposes so far.