の has a female connotation and I wanted to obtain some alternative final sentence particles.
Colloquial language in females is sometimes characterized by dropping the sentence-final だ altogether to sound less forceful/direct. So the equivalent sentence-end for colloquial male language would be のだ, which regularly (almost always) contracts to んだ in casual contexts.
From Japanese in MangaLand by Marc Bernabe:
よ：a) to sound convining, b) to express an order or a wish
さ: emphasizing effect like ね, but mainly in the area of Tokyo
ぞ： A particle only by men in informal-vulgar language, similar to よ to convey certainty.
ぜ: similar to よ and ぞ, but a bit "cooler", mainly by young men