Declension table of ?rudraka

Masculine	Singular	Dual	Plural
Nominative	rudrakaḥ	rudrakau	rudrakāḥ
Vocative	rudraka	rudrakau	rudrakāḥ
Accusative	rudrakam	rudrakau	rudrakān
Instrumental	rudrakeṇa	rudrakābhyām	rudrakaiḥ rudrakebhiḥ
Dative	rudrakāya	rudrakābhyām	rudrakebhyaḥ
Ablative	rudrakāt	rudrakābhyām	rudrakebhyaḥ
Genitive	rudrakasya	rudrakayoḥ	rudrakāṇām
Locative	rudrake	rudrakayoḥ	rudrakeṣu

Compound rudraka -

Adverb -rudrakam -rudrakāt