I don't have words for rubber so I'll do the green pen one (using eivpi 'carving tool' instead of pen):
gemba sỉlkumuednakimi eivpi mialha tavvi pila
[ˈɟɛmba ˈsi:kumʊɛʔtnɑɟimi ˈɛɪðbi ˈmɪalha ˈtʰɑw:i ˈpʰila]
gemba s-i-ỉlk-um-ue-dna-ki-mi eivpi-Ø mialha-Ø tavvi pila-Ø
preferably 2p.unag.sg-dit-present-obli-concl.infer.tr.opt-revers-1p.reci.sg-1p.ag.sg carving.tool-dat blue-dat than red-dat
‘I’d rather you get me the green carving tool rather than the red one’
Siwa has socalled multiple-agentivity in verbs. There can be an subject, some sort of auxiliary of need or obligation, an object to that auxiliary (i.e. it's subject as an object), and there must be the reversive infix -dna- (reversing on what argument the auxiliary/need lies).
I need to go - mak·um·i·mi (go·must·indic·1p)
I need you to go - sa·mak·um·adn·i·mi (1p·go·must·reversive·indic·1p)
This particular example is literally translated as:
'I would rather need you to present to me the blue/green carving tool than red'
Next (if you so chose):
I need you to show me the one you didn't take a bite out of
Siwa:
Sisyvvumadnakimi katurontủna
(lit. I need you to show to me from-unbitten-yours)
or
Sisyvvumadnakimi, iri aksuikona
(lit. I need you to show to me, which was not your-bitten out of)
or
Kahami isyvvotekina, iri aksuikona
(lit. I need that you show to me, which was not your-bitten out of)