Three important topics, the first of which is the form of vessels:
332. As regards the form of the sacred vessels, it is for the artist to fashion them in a manner that is more particularly in keeping with the customs of each region, provided the individual vessels are suitable for their intended liturgical use and are clearly distinguishable from vessels intended for everyday use.
The one “tradition” I’ve noted in many places, but have never understood, is the practice of making a ciborium in the shape of a chalice rather than a paten, or plate.
Have your vessels been blessed?
333. As for the blessing of sacred vessels, the rites prescribed in the liturgical books should be followed.[Order of the Dedication of an Altar, Book of Blessings 1068-1084]
Have you provided for a real sacrarium?
334. The practice should be kept of building in the sacristy a sacrarium into which is poured the water from the washing of sacred vessels and linens
(cf. no. 280).
A note about sacrariums and new or renovated churches. In my previous parish, this location drained into the lowest elevation on the parish property. During Spring melt, or a particularly heavy rainfall, the water would just back up into the sink, rendering it unusable. At least until we disconnected the pipes, inserted a large bucket, and drained the bucket every other day. We could count on the bucket brigade at least a dozen times a year. Curious that when the church was expanded, one beancounter asked me why we were putting in a new sacristy at another location.
The liturgical books don’t tell you how to do it, but it might be useful to know a sacrarium is more about a sink on one end and a pipe in the ground on the other.
I think I can speculate about practical reasons for the stemmed ciborium:
1. In the Eastern traditions, it facilitates intinction, which would be more difficult without the stem.
2. Generally speaking, it’s easier to get a firmer grip on a stemmed vessel than a plate or broader cup.