Remove the claws and legs. Keep these if you want to peel them separately to build up another bait or add to an existing bait.
Peel the crab. I start with the main shell then work my way to the underside. The belly plates are usually the hardest to remove but it depends how advanced in the peel it is. A very ripe one, the shell will crumble off like paper.
I wouldn’t worry about getting every scrap of shell off anyway, the fish won’t mind.
Using scissors, make a slit in the body from the tail ie cut about halfway, then work the result up a hook - the cut enables you to open the crab out a bit and make a rough sausage shape.
It may not thread very well, but just do an approximation then you can use the elastic afterwards.
Lash on well with elastic. You can use a single hook but I find a pennell is better to hold it all together. Don’t be afraid to lash it to the second hook too.
Hook size depends what you’re after, but I prefer a wide gape and for hounds usually use a Varivas BMX 3/0 or sakuma manta extra (basically the same thing).
No doubt others have their methods and bait tools and god knows what else, but that will get you a crab bait on a hook!