just found a solution but i dont really like it: (get hitboxes and origin, set model, write its hitboxes and origin)
Code:
entity_get_vector(entid, EV_VEC_origin, orig)
entity_get_vector(entid, EV_VEC_mins, MinBox)
entity_get_vector(entid, EV_VEC_maxs, MaxBox)
entity_set_model(entid,"model.mdl")
entity_set_vector(entid, EV_VEC_mins, MinBox)
entity_set_vector(entid, EV_VEC_maxs, MaxBox)
entity_set_origin(entid, orig)
entity_set_int(entid,EV_INT_solid,2)
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