Bhashya
तत् तत्र एतस्मिन्नर्थे, यथा पेशस्कारी- पेशः सुवर्णम्तत् करोतीति पेशस्कारी सुवर्णकारः, पेशसः सुवर्णस्य मा-त्राम्, अप आदाय अपच्छिद्य गृहीत्वा, अन्यत् पूर्वस्मात्रचनाविशेषात् नवतरम् अभिनवतरं, कल्याणात् कल्या-णतरम्, रूपं तनुते निर्मिनोति ; एवमेवायमात्मेत्यादि पूर्ववत् ।नित्योपात्तान्येव पृथिव्यादीनि आकाशान्तानि पञ्च भूतानियानि 'द्वे वाव ब्रह्मणो रूपे' इति चतुर्थे व्याख्यातानि,पेशःस्थानीयानि तान्येव उपमृद्य, उपमृद्य, अन्यदन्यच्च दे-हान्तरं नवतरं कल्याणतरं रूपं संस्थानविशेषम्, देहान्तर-मित्यर्थः, कुरुते- पित्र्यं वा पितृभ्यो हितम्, पितृलोकोप-भोगयोग्यमित्यर्थः, गान्धर्वं गन्धर्वाणामुपभोगयोग्यम्, तथादेवानां दैवं, प्रजापतेः प्राजापत्यम्, ब्रह्मण इदं ब्राह्मं वा,यथाकर्म यथाश्रुतम्, अन्येषां वा भूतानां संबन्धि- शरी-रान्तरं कुरुते इत्यभिसंबध्यते ॥
In plain words
Let's take the verse apart, phrase by phrase. 'A goldsmith' — peśas just means gold, and a peśaskārī is simply someone who works it: a goldsmith. 'A portion of gold' — that means he cuts off and takes hold of a piece. 'Another, newer, more beautiful form' — genuinely fresher than the old design, finer than before — and 'fashions' just means shapes, molds. Now, everything after 'thus indeed does this self' works exactly as it did in the earlier verse. The raw material here is the same five elements — earth through space — that were already explained back in the fourth book as 'the two forms of Brahman.' These five, eternally on hand, play the same role gold played there. Ground down and reworked again and again, they become one new body after another — a newer, more beautiful form simply means a specific new bodily configuration, which is just what 'another body' means. And where does that body land? 'Belonging to the fathers' means good for the ancestors — fit for life among them. 'Belonging to the gandharvas' means fit for their kind of enjoyment. The same goes for the gods, for Prajāpati, for Brahmā — each according to the action performed and what scripture says about it. And if it belongs to none of these but to some other kind of being, that phrase still connects back to the same verb: he makes that body too.
Close to the Sanskrit
That, on this point: as [the verse says], 'a goldsmith' — peśas [means] gold; he who makes [things] out of that is a peśaskārī, [that is] a goldsmith. Of gold, [that is] of gold, a portion — [that is,] having taken away, [that is] having cut off, having seized — another, newer than the previous particular design, [that is] quite fresh, more beautiful than [its former] beauty — a form he fashions, [that is] constructs. 'Thus indeed this self,' etc. — as before. The five elements beginning with earth and ending with space, which were explained in the fourth [book] as 'two, verily, are the forms of Brahman' — these, which are only ever the eternally-appropriated ones, standing in the place of the gold — these very ones, crushing and crushing again, [he makes] another and another body, a newer, more beautiful form, [that is] a particular bodily configuration, [that is,] that is the meaning of 'another body' — he makes: belonging to the fathers, or [that is] beneficial to the fathers, [that is,] fit for enjoyment in the world of the fathers, that is the meaning; belonging to the gandharvas, [that is] fit for the enjoyment of the gandharvas; likewise, belonging to the gods, of the gods; belonging to Prajāpati, of Prajāpati; belonging to Brahmā, this, of Brahmā, or, according to [one's] action, according to what is heard [in scripture]; or [a body] connected with other beings — [this] is construed with '[he] makes another body.'