What scale? Verlinden produce (although I think they may be OOP) both a german SS sniper and a British para sniper in 120mm.
Ghuili suites are usually a pair of overalls with pieces of cam net and scrim (old hessian from sandbags) sewn to it. Mostly design is left to the individual to come up with their own, and I have read that at the start of the sniping course the ghuili suit is covered with 'garnish', but as the snipers confidence increases, it gets pruned back somewhat.
To make one in 120mm I would use lots of little pieces of muslin cloth torn and cut into little bits, muslin cloth has the advantage of being very close to hessian in 120mm. I would also add other strips from tissue, and maybe some natural foliage like moss etc.