Making up bungee cords to custom length is pretty easy. I have used the following process for 10+ years to make up custom length bungee cords for my sailboat's tarp that needs replacing about every six months... It takes much longer to explain than to do, but here 'tis.....

At Orchard Supply (for sure), and probably Home Depot, you can buy the hook ends and cord separately, or you can use the ends off an old cord with new "virgin" cord cut to length, or cut a new made up cord to length and reinstall the cut off end on the shortened cord.

Be sure to get the proper diameter hook end for the cord size... Bungee cords and hooks are sold in several diameters, and the hook end's gotta be the same size as the cord. or you may run a 2005 test of Newton's "action/reaction" law of physics The failure of such testing is often accompanied by languge unsuitable for young 'uns, and may cause unplanned trips to the Emergency Room... Bungees do store a lot of energy....

Measure the length of cord you need, adding about 1 1/2 inch for each hook end you will install. Cut to length, remembering to take into account the length of the hook ends for the overall length of the bungee. (This is really critical in making up short cords)

To attach a new hook end, cut a piece of coat hangar wire about 3/4 - 1 inch long and bend it into a shallow "V" shape (around 30 degrees from straight).

IMPORTANT NEXT STEP - Slide the hook end on the bungee cord - be sure it is oriented properly (e.g.; hook facing toward the correct end...... don't ask).

Bend the end of the cord back on itself about an inch, and hold in place with a vise or vise grips (or pliers held by a willing and patient assistant), leaving about 1/2 inch of the bent-over "knuckled" end of the cord exposed.

Place the shallow "V" of the coat hangar wire perpendicular to the length of the cord and place the ends of the coat hangar wire in a pair of serrated jaw pliers. Bend the coat hangar around the doubled over bungee cord and crimp as necessary to ensure the wire is tight against the bungee cord.

Trim off the excess cord length with a sharp knife, razor or XActo blade, leaving about 1/4 inch of the cord end beyond the coat hangar wire crimp.

Bring the hook end down on the doubled over cord end and pull on it to check it for security... Pulling about 20 lb will confirm it is properly seated. Suggest being careful with this step, 'cuz if your hangar wire crimping was faulty, the cord may smite thee...

DONE!!

Have also used tyraps instead of coat hangar wire in a pinch, but only for temporary, light load cords...

Cheers!

Jim