Filament Feed Report should be your first stop for filament…
It’s still a work in progress, but it’s close to where i want it to be.
Updates every 8 hours, starting at 6am, 2pm, 10pm. Each run takes about 30-40 minutes to complete and for posts to go up, etc. Time the run started is in the title of the report post.
Each run starts off requesting data on around 20,000 items, which is pretty much the entirety of the filament section, excluding items with shipping and completely bullshit sellers. This includes all variations (all colors, sizes) at all listings. They then get “rinsed” through a variations of filters to score each item based on various criteria, narrowing them down to 500 items to upload to the feed, and 300 to select for the report.
Items in the report can be sorted by Score, Price, Drop, New and $/kg, which is a new and very useful feature (though it does still occasionally misfire). There are dropdowns for Type and Brand (eg. SUNLU and PETG), so you can quickly select to see something like – Overture PETG by $/kg, etc.
Score is a bit convoluted. It will need a whole other/long post to really make it make sense, but in a nutshelll…
All items are assigned a base target price they should meet (PLA is $10). This base price then gets adjusted with various modifiers for Quality, Speed, Novelty, Extrusion type, Fill, Finish, Brand reputation and bulk quantity. If the item hits the target price, it gets a score of 15 (otherwise 0). This doesn’t make the item “a deal”, it just means it’s in the right ballpark in terms of pricing already, giving it a small boost in score, which is important considering the next score.
Next score is Drop. This is the percentage drop from the old to the new price. There is a big difference in quality of drop from Typical Price (what the item actually sells for, according to Amazon’s own price history) and List Price (whatever the seller made up, and can change at any moment). To put it in the simplest way possible – price drops from List Price are often bullshit. So, to make at least some kind of sense of it, drops from Typical are counted at x1.5, and drops from List are x0.5. This means that an item with a Typical Drop of 10% gets a score of 15, and an item with a 30% drop from List Price also gets the same score of 15. It’s not a perfect formula, but it does help to normalize things at least a little bit.
Hit% is a modifier. If the target base for PLA was $10, and it shows up at $8, then it’s 20% better than expected. This gives the sum of the previous two scores a boost of +20%. If it shows up at $12, it gets a -20% deduction.
Brand reputation once again is counted here. It is tougher for items with good brand reputation to meet the required target price. Again, using PLA at $10 as base – Overture has a brand rep score of 30%, so Overture PLA immediately has a base of $13 it needs to meet to hit the target price. Because of this, the previous score of Hit% often suffers. So Brand reputation is counted again as an offset.
And finally there is freshness. Any item that’s brand new (last 24 hours) gets a +5 added to the score. For every day this item stays at the same price it gets -2 deducted, for up to two weeks. This gives the newer items a little bit of a better score, and tanks the stale deals.
As long as that explanation was, it was still very much a TLDR version. There are a lot of little factors at play that adjust/affect the score, and i am still very much playing with all the “buttons”.
The whole point of this long explanation – i did my best to try to balance discounts with already good prices/values, and try to factor in stuff like Brand, etc. It’s not perfect, but it does a pretty decent job of picking out the better deals most of the time, and will improve in time as i make tweaks.
Like i said in the title – this should be your first stop for filament 🙂
