I’ve not used it, but the Beaufort Mistral pencil is available for 0.7 or 0.5 mm lead. Pairs with their rollerball or fountain hardware. Turners Warehouse is their sole USA distributor. I do a fair amount of their rollerballs in Mistral and Leveche—platings, fit and finish are top notch. Kit prices are high, but seem like a value once I work with them. All I here at the moment are a few Leveche fountains and maybe a roller or two in kits, probably a few finished pens. Cover the postage and I’ll send you a kit or pen to evaluate. If you’re headed around the southern tip of Lake Michigan soon, I’m 15 minutes from New Buffalo—cost drops to a coffee!!
Earl