ce:
Thats correct. The word make is the greek word see rom 9:21
poieō and one of its meanings is to ordain or to appoint.
The word clay is to denote man in his uncreated mass, as Adam was before God formed him from the dust of the ground.
The word dust as used in gen 2 for Adam being formed out of the dust of the ground is the hebrew word aphar:
dry earth, dust, powder, ashes, earth, ground, mortar, rubbish
a) dry or loose earth
b) debris
c) mortar
d) ore
mortar is a clay substance used for building walls in lev 14:
42And they shall take other stones, and put them in the place of those stones; and he shall take other morter, and shall plaister the house. see vs 45 too.
So Paul is saying, that God had the absolute right in the creation of man, to purpose some as vessels of wrath [ for their sins] and to purpose or appoint some as vessels of mercy for their sins.
Now mind you this is all in the context of why so many ethnic jews are not becoming believers in the Messiah, which appears to mean God's salvaic purpose for Israel has failed. Paul's argument is not all Israel [National] are Israel [Israel of God, children of promise] 9:6-8 Then He sets out to prove that supposition. For all men particularly in this case jews, have not been appointed to salvation through the Messiah. However the clay reference goes back to men in general, not nationality specifically, for in Adam was the representation of all nations and bloods acts 17:
26And hath made of one blood [Adam] all nations of men for to dwell on all the face of the earth, and hath determined the times before appointed, and the bounds of their habitation;
Notice, He hath appointed the bounds of their habitations. Heaven and its Glory is noted as an habitation lk 16:9
And I say unto you, Make to yourselves friends of the mammon of unrighteousness; that, when ye fail, they may receive you into everlasting habitations.