If you live in a first-world country it's just cheaper to buy a new one from Harbor Freight but if you still want to practice your welding skills or you have some tools for metal working and have no care for your own safety, this is for you.

Supplies

I used 8 meters of 4x4 inch square tubing for the structure and 90 deg angle iron for braces and supports

Some 1/2 inch bolts, nuts, and some scrap metal

and 2x2 kinda thick with rebar braces on top

Step 1: Cutting and Welding

These are a rough estimate of the dimensions I used but you may need different ones if your working in a smaller car, so just use this as an inspiration.

Cut everything in your desired dimensions and weld everything up as it lines up.

Step 2: Paint and Accesories

1/2 inch bolt into the floor jack with washers to secure it in place and then a bolt into the round tube that lifts the hoist.

Easier to guide yourself with the photos

Step 3: Test Time and Glory

Time to test all your work and welding skills, be careful with this guide I don't recommend it if you care about your own well being but sometimes things have to get done some way.

Be careful and have fun!