Saturday Night Question

[Fuukanou]

Ahh this one's been bugging me for ages:
Full kanji: https://pastebin.com/819Kfv5q
Full romaji: https://pastebin.com/Yt1Skwfs
Full translation: https://pastebin.com/McuJSW7k

Problem 1
チャンス到来モノに出来たら
じゃあねお先に失礼します
そんな強がり空回りかな

Once a chance presents itself,
'Okay, I'll take my leave here'
I wonder if acting tough like that is getting me anywhere…

What's bugging me is the モノに出来る bit. I thought it meant 'make one's own' but I don't really know how you make getting a chance your own. Is it 'once I'm able to take advantage of a chance that appears' or something like that?

Problem 2
飛び散ったパズルの忘れかけた言葉とカケラ探し
隙間もなく埋めたいんだ
戻らない時間と作り上げた小さな過去の答え
次の扉開けたのなら

I search for almost forgotten fragments and words from a scattered puzzle
I want to fill it in leaving no gaps
I'll find the time that won't come back, and answers from a small fabricated past
Once I've opened the next door…


It seems like it's just a random fragment floating in the verse so I assumed it was an example of what is being searched for. I also have mental bracket problems going on as to whether it's (作り上げた小さな過去)の答え or 作り上げた小さな(過去の答え) [so if it's a normal-sized answer from a small fabricated past or a small fabricated answer from a normal-sized past]. Am I just missing something here- are there any rules to this or is it a completely case-by-case thing?