Peter Masak had winglets on his Nimbus 3 at the 1989 WGC. There is a Nimbus 3 F-CFUN flying with what looks like Maughmer Winglets. There are some examples with Borowski winglets which have a swept back shark fin type design. There are also some Nimbus 3 with swept back wingtips (Nimbus 4 style) but without winglets. All these examples are installed on the single seater. I have not yet seen or heard of a Nimbus 3D with winglets. Since the wing is basically the same, all these mods should also work for the 3D.

I would also be interested in further information on the topic...