Yoma, chapter three, Mishnah ten. At the end of the previous Mishnah we were told that one of the Kohanim Gedolim, ben Gamla, improved the lots used for drawing between the two goats on Yom Kippur, replacing them from wood with gold. Our Mishnah continues and lists additional individuals who made improvements and repairs in the Beis HaMikdash.
"Ben Katin asah shneim asar dad la'kiyor":
Ben Katin, a Kohen Gadol, installed twelve spouts in the kiyor (the laver). The kiyor is the large vessel that held the water in which the kohanim sanctified their hands and feet before the service. "She'lo hayu ela shnayim" - until then it had only two spouts. The purpose of the twelve: so that all twelve kohanim engaged in the daily tamid service could sanctify their hands and feet at one time.
Although we learned above that thirteen kohanim were involved in the tamid service, the first of them was the one who slaughtered, and slaughtering does not require a kohen - it is valid even when performed by a non-kohen, and therefore it does not require sanctification of the hands and feet.
"V'af hu asah muchni la'kiyor":
Ben Katin also installed a "muchni" for the kiyor - a sort of machine (and opinions differ as to the nature of this device) - "she'lo yihyu meimav nifsalin b'linah". The kiyor is a sacred vessel, and anything placed into a sacred vessel for the purposes of the service is subject to the laws of linah: if it was not used during the day and remained in the vessel through the night until the following morning, it becomes disqualified. So that the water of the kiyor would not become disqualified, ben Katin installed the muchni. Some explain that this was a system of pulleys that allowed the kiyor to be lowered into the well of water, so that its water would be joined to the water of the well and would have the status of well water, which is not subject to the laws of linah.
King Munbaz and Helene his mother:
"Munbaz ha'melech hayah oseh kol yedos ha'keilim shel Yom HaKippurim shel zahav" - he made all the handles of the vessels used on Yom Kippur out of gold.
"Helene imo asesah nivreshes shel zahav al pis'cho shel heichal" - Queen Helene made a golden candelabrum-like ornament that hung above the entrance of the Heichal. When the sun rose and struck it, the ornament sparkled with the sunlight, and all the people of Jerusalem knew that the time for reading Shema had arrived.
A golden tablet - Helene also made a golden tablet on which the passage of the sotah was written, so that the kohanim who needed to write portions of the sotah passage on parchment (in order to erase them into the sotah water) would not have to bring a Torah scroll, but could copy the words from the golden tablet.
"Nikanor na'asu nissim l'daltosav":
The Mishnah concludes with Nikanor, who ordered his doors in Alexandria of Egypt and had a miracle performed for them. The doors were made of a special wood and plated with copper, and when they were being transported by ship a great storm arose. They took one of the doors and threw it into the sea to lighten the ship, and when they wanted to throw in the second, Nikanor would not let them, and was even prepared to be thrown in together with it - and in that merit the storm subsided (and this matter itself requires explanation). Nikanor grieved over the loss of the one door, but when the ship reached the port of Acco, the door that had been thrown overboard was found directly beneath the ship - which is a miracle in itself, since it should have sunk. Because of the miracle that took place with them, when in the end all the other doors of the Beis HaMikdash were replaced with gold, Nikanor's doors remained in place - these are the doors of the Azarah, through which one entered into the courtyard of the Beis HaMikdash.
In conclusion, the Mishnah mentions all these individuals for praise (and there is a version that reads that they used to mention them for praise), since they are worthy of praise for the improvements they made.
In summary: This Mishnah listed the improvements made in the Beis HaMikdash: ben Katin - the twelve spouts of the kiyor, and the muchni that prevented its water from becoming disqualified through linah; King Munbaz - golden handles for the Yom Kippur vessels; Helene his mother - the golden ornament above the entrance of the Heichal, and the golden tablet on which the sotah passage was written; and Nikanor - the copper doors for which a miracle occurred and which therefore were not replaced with gold. And all of them are mentioned for praise for what they did.