toning down the fresh chilli picquancy

Most of the heat in a chili pepper is concentrated on the ribs and membrane that holds the seeds.

By cutting out those parts, and using only the fleshy part of the fruit, you will get less heat.

The heat can also be mitigated by dairy or fatty ingredients in the dish in which you incorporate the chili, as they tend to help wash away the hotness in the mouth.

If you want chili flavor rather than heat then add the chilis in whole, they will keep their shape well. Just be careful about eating them, they will be fearsomely hot!

Advance warning: I haven't tried this.

It seems that you don't want to remove the ovaries because that would affect the shape, but you do want to remove the capsaicin from them. It's soluble in fat and alcohol, so you could try making a small hole in the bottom and pumping a light vegetable oil or vodka through from the other end using a syringe. Obviously you're likely to end up with some solvent trapped inside, and you might also wash away some of the flavours you're trying to preserve, so experimentation would be necessary.

I've seen hot chilies blended with red bell pepper (seeds in) to add volume without impacting heat. This works well for Harissa sauce, where tomato is unwelcome.

Whole chilies are used in Indian dishes, but cooks advise care. Breaking the peppers will seriously overheat the dish.

I suspect blending hot and mild chilies is the best approach, but I'm looking forward to other suggestions.