Q:

How were the "dust recepticles" installed on the Apollo 17 LM floor?

This answer quotes Apollo Program Summary Report and includes the sentence:

During the Apollo 17 mission, dust on the lunar module floor was swept into floor receptacles which were sealed before lift-off, but some dust was still present in the cabin atmosphere after lunar orbit insertion. 

Question: Was the floor of the Apollo 17 lunar module modified from previous LM's to have these recepticles added (I'm imagining some hole in the floor with a sealed box below it), or are these above-floor receptables affixed to the floor? Are there photos or drawings?

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A:

There isn't much documentation on the design or evolution of the LM floor.  There are holes where dust could plausibly be swept into, but it's not clear whether they were designed for that purpose.
The Apollo 17 Mission Report, p. 10-15 calls them "holes": 

Prior to ascent from the lunar surface, the cabin activities included covering all holes in the lunar module floor into which dust had collected or could be swept. Although considerable dust appeared in the cabin upon insertion, taping the holes definitely prevented a major dust problem in zero-g.

The Apollo LM Operations Handbook, p. 1-6 mentions "handgrips" recessed in the floor:

The crew compartment deck measures approximately 36 by 55 inches. It is constructed of aluminum honeycomb bonded to two sheets of aluminum alloy. Non­flammable Velcro pile strips, which contact hooked Velcro material on the astronaut boots, are bonded to the deck surface.  Handgrips, recessed in the deck, aid the astronauts during egress and ingress through the forward hatch.

Originally I thought that the ascent engine cover my also have had pockets to sweep dust into, but I am no longer convinced of that.
It seems that there may have been changes to the LM floor throughout the program.  Compare this picture of a LM at KSC:

to this one from the Smithsonian:

There certainly are holes in the floor where dust could be swept into.  And at least one of the slots on the floor of the Smithsonian photo looks does like a handhold.
Sorry, no ashtrays.

