The Avtinas family was appointed by the Sanhedrin to provide the incense, and they were exclusively responsible for its production, which was done in the chamber named for them, the Chamber of Avtinas. We have learned that this chamber was located in the south side of the court, over the "water gate."
The Midrash (Shir HaShirim Rabbah, 3:4) provides several poignant glimpses of the Avtinas family, which tell us something of the great dedication that burned in their hearts for their holy occupation:
"The Avtinas family were expert in the preparation of the incense spices, and knew how to use the herb ma'aleh ashan, which caused the smoke to rise. But the rabbis were critical that they refused to teach these things to others, and suspended them from office. The sages sent to Alexandria for skilled craftsmen, and engaged these others to try and duplicate the Avtinas' incense. These craftsmen were expert in the spices, but they could not make the smoke rise up in a straight column like the Avtinas family... the smoke from their incense immediately diffused and scattered.
When the sages saw this, they remarked that everything which the Holy One created, He created only for the sake of His own honor, as the verse states (Isaiah 43): 'Every one that is called by My name, for I have created him for my glory; I have formed him, yes, I have made him.' They returned the Avtinas family to their task, and doubled their wages."
"But the wise men asked them: 'What is the reason that you do not share the secret of your profession; why do you not want to teach others?'
They responded: 'Our fathers passed on a tradition to us, that one day the Holy Temple will be destroyed. We did not want to teach our secret, so that it does not fall into the wrong hands, the hands of idolators; and one day, the holy incense offering which we presented before the Holy One would then be used for idolatry.' When the rabbis understood that this was the reason for their silence, the Avtinas family was greatly praised."
"It was also told that no member of their family ever put on perfume. And when one of them would marry outside the family, they would make an agreement that the girl should never wear perfume. And all this was so that no man should ever suspect that they used the secrets of the holy incense for their own personal use, as the verse states (Numbers 32), And you shall be clean before G-d and Israel'."
"Rabbi Akiva related: Shimon ben Luga told me that once (after the destruction of the Holy Temple), he and a young lad - a descendant of the Avtinas family - were gathering herbs in the fields. 'I noticed that suddenly the boy wept, and then laughed. I asked him, my boy, why do you cry?' And he told me, 'For my family's honor, which has been diminished.' And why did you laugh?', I asked him. 'Because the greatest honor is reserved and established for the righteous in the future world. And in the end result, the Holy One will gladden his descendants, may it be speedily.'"
"I asked the boy, what did you see that reminded you of all this?' And he told me 'As we were gatheriing, I saw the plant ma'aleh ashan before me in the field.'
'Show it to me!' I exclaimed. But he told me, We have a tradition never to show it to any man.'
Only a few days passed, and that child died. Thus he did not reveal it to anyone."