This is one of those projects that's been on the 'to do' list for a long time. Just a simple three point attachment version of
suspenders, non-adjustable and made to fit me. I used
shock cord for the core,
Flat Gate Clips from
County Comm for the attachments to clip to my pant's belt loops, and then knotting over the shock cord with paracord, tying the Solomon bar/Portuguese sinnet/cobra stitch.
I started with about 10 feet of shock cord, looping the center of that length onto one flat gate clip, measuring about a foot down with both cord ends to tie a
cross knot, splitting up the two cords and measuring about three feet down each, tying a
scaffold knot to each of two more flat gate clips.

I had about a 60 ft length of black
paracord that I cut in half, then used each to tie Solomon bars around each of the two single lengths of shock cord to where they meet at the Chinese crown knot. I had just enough paracord left at this point to make a couple more knots on the other side of the crown knot, tucking/pulling end strands under the knot work. I used another 12 ft length of paracord to tie a Solomon bar from the third flat gate clip up to where I ran out of cord with the other strands, then tucked the excess under the knot work to finish. If I'd had more paracord available, I would have started with a 100 ft long hank, cutting that in half, then once the two shoulder straps were covered, I would of had plenty to continue down around the single back length of shock cord.

Since these are not adjustable, I made a guesstimate with the single section from the back and the two shoulder straps down the front, with all the flat gate clips attaching to the belt loops of the pants I wear, and where the pants fit around me as I wear them. The shock cord allows the suspenders to stretch(old example
video link I made with Solomon bar over shock cord) when sitting, standing, bending, and moving about. If you were to just use paracord alone, you'd likely find the suspenders uncomfortable to use without any give in them. I've found a good fit with just enough tension in the cord to keep the shoulder straps in place while standing, but not too much or you'll find the back attachment pulling your pants up to the point of giving yourself an uncomfortable wedgie...

The initial fit is good, but I'll have to see how they do over time. I have other suspenders that I occasionally wear to help keep my britches up, with a three point belt attachment
Perry type suspenders, and a two point side clip type from
Duluth Trading Company.
Suspender clip attachments come in a variety of styles, shapes, and sizes, but generally have wide attachments for use with elastic webbing. You may find some out there that can be cannibalized for use with making your own paracord suspenders...

You could try knotting directly over/around elastic suspenders, anchoring the paracord at the attachments at start and finish, similar to knotting over
bag/pack/gear handles, but I haven't tried it with my suspenders, so I dunno if it'd work out or not. Another possibility is to make loops on the ends of the shock cord, to fit over your belt, instead of using attachments.
Some folks wear either a belt or suspenders, but when I wear suspenders, I use them along with a belt, worn over a tucked in t-shirt and underneath a button down shirt with straight hem that's meant to be worn untucked.
There's a
thread on the DIY Tactical forums with some neat ideas of using side release buckles and webbing loops instead of the metal grip clips with low-profile suspenders.

A few more photos of another pair of shock cord suspenders with fixed loops instead of attachments, to use with a belt. Started with a 2" loop and cross knot, down a foot then another cross knot, and finishing with a pair of
broach knots for the shoulder straps. The other couple of photos show starting the knotting from the broach knot ends and ending at the other side of the cross knot, with the end strands to be tucked under the knot work with hemostats...

When making your own suspenders, to figure out your shoulder strap length for the shock cord, put on pants and attach the back part of your shock cord suspenders(loop or attachments), then pull each of the shoulder pieces over your shoulders down to where they'll either attach to your pants or belt, and decide the strap length on the tension you want, taking into account what attachment you'll use, then add the attachment or loops on the strap ends. You're left to choose what type of paracord knot work you want to tie over it...