An artificer uses his Magical Tinkering ability to Imbue a tiny nonmagical object with light. 

What if that object was a ball of twine? You then attach one end to a projectile that is then launched, unfurling the ball as it goes. For this example let's just assume in a straight line but I'm sure there are plenty of ways to unball the twine all of which will have basically the same result.

I see a couple outcomes. The entire ball of twine is illuminated and so as it unfolds you end up with a corridor of bright light 5 feet wide and another 5 of dim.

Or, only the surface strands were illuminated and you have smaller individual pools of light. This creates the possibility of shadows which I kind of prefer. The other draw back to the second result might be that a much shorter length of the twine is affected.

I'm probably going to go with the second. So the artificer would end up with an unfurled 50 foot strand of twine with the first 30 feet intermittently lit up. 

Looking for thought and opinions.

The following reference is from the DMG page 247.

OBJECT HIT POINTS

Size.                                                                    Fragile             Resilient
Tiny (bottle, lock)                                                2                             5
Small (chest, lute).                                              3                            10
Medium (barrel, chandelier)                              4                             18
Large (cart, 10-ft.·by-10-ft. window)                 5                             27

so using the size description of a bottle or a lock as a standard for a tiny sized object, I think a ball of twine would easily qualify.

regarding how exactly the twin would interact with the magical tinkering feature, I’d say the entire twine would give off light since there’s no dimension limitation.

the light cantrip is similar with the exception that limits effected objects by “10ft in any dimension” instead of object size.

What constitute a tiny object is up to DM, like Bobbybaker posted the DMG provides exemple in the form of bottle, lock for size comparison.

Personally i don't think a ball of twine would qualify as a 20 feet long string is an item of a muchbigger size than tiny even if you can roll it into a smaller ball.If you go down that route, you will quickly end up with larger items that folded, bent etc.. to be of tiny size.

I would think of it as something that you can easily hold in one hand for medium/small sized humanoids. Even though a ball of twine can be unrolled to a long length I still would consider it tiny as it takes up so little space unrolled. 

But it would be DM choice what qualifies to address Plaguescarred’s concerns. 

Of course the answer is always DM discretion (which I find to be a lazy cop out of an answer) which means everything can be allowed, the DM just has to be imaginative enough to deal with the outcomes. So let's focus the discussion there.

Quote from Plaguescarred >>

What constitute a tiny object is up to DM, like Bobbybaker posted the DMG provides exemple in the form of bottle, lock for size comparison.

Personally i don't think a ball of twine would qualify as a 20 feet long string is an item of a muchbigger size than tiny even if you can roll it into a smaller ball.If you go down that route, you will quickly end up with larger items that folded, bent etc.. to be of tiny size.

 Let's explore this a bit because it's a good point. Personally I'm not fully convinced to rule out the ball of twine as tiny. So let's compare some of those other items to see how game breaking it is. For me it would first depend on if the item could actually fold, bend, crush, or alter its form to tiny. 

I usually consider tiny as something you can fit in a single hand or put inside a 6x6 box just as the references cited indicate.  Let's take a cloak for example, you could wad it up or fold it but I don't think you could get it to tiny range. A scarf? Sure. Now I can't think of any effect that you could put on a scarf that would be game breaking. But if someone else can please speak up. 

If we go back to the initial example of the twine I don't see how a unrolled ball of twine producing 30+ feet of light disrupts the game. Sure it might ruin the shadowy ambush you had planned because the area is now lit, but like I said, you just have to be creative with the results. Which is why I like the intermittent option better since as a DM I can always just adjust the shadows to land where I want them. 

But give me some other reasons of how creative ways to get the tiny tag might break the mechanic a bit.

If an object were considered Tiny, then a Psi Warrior would be able to summon it to their hand with Telekinetic Movement. That's the most I could think of on the matter of Tiny objects.

Quote from MrJanuary812 >>

I don't see how a unrolled ball of twine producing 30+ feet of light disrupts the game. Sure it might ruin the shadowy ambush you had planned because the area is now lit, but like I said, you just have to be creative with the results. Which is why I like the intermittent option better since as a DM I can always just adjust the shadows to land where I want them. 

 It may or may not not be disrupting but i'm not ruling based on effectiveness but on pure size evaluation and something bigger than tiny size cannot be counted as tiny size if folded or rolled up, to me it just doesn't change the initial size any more than a medium size creature doesn't become small size because it curls up in a ball.

Creature sizes are based on the area of a battlefield they "occupy", a Medium creature occupies a 5x5x5 foot cube, Small is half that in all dimensions, Tiny is half again. However many creatures extend beyond this area, as Medium creatures can be taller than 5 feet, ancient dragons have long necks and tails, and huge wingspans that won't fit inside a 20 foot cube, so it's okay to extend beyond the space, it just doesn't have an impact on the game mechanically.

I would use this same behaviour for a Tiny object; while it can extend beyond the edges of the space when unrolled, the effect won't, so you would end up with a light originating either from one end of the string (the space from which it was unrolled) or somewhere in the centre.

Exactly, the feature Magical Tinkering refers to an item's original size, not the space it takes up.

So if you prefer, a medium size creature measuring 4-8 feet or a small one measuring 2-4 feet still does when curled up in a ball and it's size category still remains. The original size of it remains the same wether it's folded or not. A large jeans size remains when folded, a 10 feet x 10 feet gazeebo is  still large when folded in a box , while it does take less space, it's integral size remains the same.

So if the DM judges that a 50 feet long string is tiny it will still be when rolled into a ball, and if it judges it's small or medium sized, it will still be when rolled up too.

Here's how I'd rule it. The amount of light is spread across the whole. So with each successive size increase the light range is reduced. If unfurled to a small size, the bright and dim light is reduced by half, and so on. Medium half again, large once more, huge and finally gargantuan (20 feet+). The light is now 1/2^5 or 3.25% as bright.

Congratulations, you've created the equivalent of a very dim string of LEDs.

Is this a cool use of the feature that is creative and doesn't really provide a huge advantage on its own? Yes.

Does it set a troubling precedent of enchanting something based on its size that then unravels/unfolds to something way bigger? Also yes.

That being said, I'd ballpark it to say the string casts a line of dim light 5 feet wide along its length with the warning that I may not allow extrapolations of this concept.