Bruises are where blood leaks out of teeny vessels. To be visible they need to be under the skin, and of contrasting enough color to be seen through the melanin and the skin itself.
So youth, thickness of skin, melanin and genetics are factors.
Okay, so there needs to be a vessel that springs a leak for long enough that the blood and blood products can leak out.
Easiest thing to try first is a not so warmed up ass, a few good impacts (the wider the implement, the more dispersed the forces, so a narrow paddle like a cricket bat shape is a great choice). Have a heating pad on high. After last impact, sit on it. Let the heat draw out blood, and gravity send it right to skin for several minutes. Repeat as you can until you see light bruising and then stay put for 10 minutes or longer.
A little blood thining can add to the volume too. Things like garlic oil pills, avoiding leafy greens a week before hand (vitamin K in them slows bleeding), some baby aspirin, alcohol, and any NSAID are all gonna be blood thinning.
Anon, it may have nothing to do with your pain tolerance. He may be just good at warming you up enough that bruising doesn’t happen easily is all.
If it’s his marks, and not specifically bruises, you’re after…
Canes tend to welt. Whippy, little stingy ones will leave a fine welt. Bite marks. Scratch marks. Wheel marks (like a kinky connect the dots). Rope marks (tend not to last more than a few hours). His cum dried onto you and left in place. Erotic body writing. (Use a felt tip style hypoallergenic waterproof eye liner and let dry. Won’t rash. Won’t stain skin like markers. Stays put, even in water. Can be taken off with makeup wipes in an emergency.)
See yourself as his blank canvas. Let him create you by expanding the palette.
Hope this info helps you get to where you’re wanting to go.