@TurdPooCharger @lone_wolf323 I'm sorry for being short with you.
I'm not looking for emulators or to make my DS into a setup for playing retro games. I'm trying to simply make the DS itself play like an arcade/console by making an arcade-shaped mold for the screens to fit in. I am fully aware that I could just emulate, get a capture card, etc. I just didn't want to go that route. I'm totally okay if what I'm looking for is not possible. I'm not totally against getting a capture card, but I wanted to see if there were alternatives (which is why I was being specific in the OP). I know that it is possible to buy replacement ribbon for the screen, which is why I asked if there was a longer one. I found somebody who soldered a snes controller to their DS lite; no cfw. Going off that, I figured it was worth it to see if somebody knew enough about the DS hardware to answer my question. Like I said, I can admit defeat. That's totally fine with me, it doesn't really matter. But I've already asked several people who assumed I didn't know about emulators or capture cards and didn't actually answer my question.
Your mindset reminds me of people who rather walk up 10 flights of stairs in a sketch area that's littered with used heroin needles and smell of bum piss in every step rather than taking a somewhat grimy elevator because of the aversion of getting stuck in a cramped one that might happen chance to break down on you while you're alone with dwindling supply of fresh oxygen.. It is a sort a stubbornness with a weak hint of valid reasoning.
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Everything you listed is possible to mod onto a 3DS but with a high price tag and immense technical expertise. If you don't go the Katsukity capture card route or can't stomach paying arm & leg for that kit install service, you have to custom fabricate your own. The reason why you can't simply buy nor make an extension ribbon flex cable from the motherboard's video output and connect it to just any LCD panel is because of the uncommon (400x240) WQVGA resolution and Nintendo's propriety(?) connectors. There are hardware calibration files,
HWCAL0.DAt and
HWCAL1.DAt, on the 3DS CTRNAND specifically tuned to the LCDs that came with your unit from factory. You also run into power supply issue for the bigger display and discrepancy for 3D mode where resolution is really 800x240 due to the 3D mode parallax design. You can try to find a suitable, larger, substitute native res LCD at
panelook.com, but I doubt you'll find something that matches or works with minimum fuss with the 3DS systems.
Now, if you want to use the original top LCD and just add an extension cable, that's actually not as bad if you know how to custom fabricate or special order such a item with those propriety connectors from China.
If not the Katsukity card, there's making your own using something like this:
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As for hardware based controller redirection input, documentation of test points is rather poor for the 3DS systems. There is a known recording for the o3DSXL as a starting point:
You might have better results using a software approach like the 3DS homebrew app
3DSController.
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I won't touch upon creating your own gaming case or shell housing. That's its own field with lots of subjective creativity.
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Your selection of retro & classic games are extremely limited if custom firmware and warez rom collection are out of the question.
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The best way I can describe your proposed setup in analogy.
It would be like you baked a cake with subpar ingredients but excellent cooking techniques and timing. Eating your cake would have been passable or pleasant enough but you didn't put the extra effort in adding little touchings and decorations, like sprinkled chocolate chips, whip cream dressing, or strawberry crown topping. It's like you're trying to make the best plain cake with skills alone but all that leads to is mediocrity. While it was never going to be gourmet, those who eat your cake are sad to know your signature homemade style cake had potential to be yummy. While your friends, family, and guesses may not tell you this, they secretly wonder what other strange tastes and preferences you harbor.
At the end of the day, the only person that matters is whether you enjoy you own cake.
