diff --git a/notes/3D printing/Filament.md b/notes/3D printing/Filament.md
index 9e1ce21..24528d3 100644
--- a/notes/3D printing/Filament.md
+++ b/notes/3D printing/Filament.md
@@ -156,3 +156,22 @@ Also known as acrylic plexiglass, the high transparency of PMMA is the only adva
| -------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| - Highest transparency thermoplastic
- Can be buffed to a frosted/polished surface
- High UV resistance
- Relatively affordable
| - Horrible bed adhesion
- Bad layer adhesion
- High coefficient of thermal expansion leads to constant print failures during or after the printing process
- Very brittle
- High water absorption |
# TPU (Thermoplastic Polyurethane)
+TPU is the most common flexible filament
+
+| Pros | Cons |
+| ------------------------------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------- |
+| - Flexibility
- Cheap
- Wide range of colors and hardnesses
- Perfect layer adhesion
- Basically shatterproof | - Permanently bonds to most build plates (use gluestick)
- Very high water absorption, needs to be dry to print well |
+## Variants
+### TPU (~99D)
+- Harder than a skateboard wheel
+- Basically rigid
+- Useful because it's "shatterproof"
+- Often used for combat gear or robotic applications
+- Easiest TPU variant to print
+
+### TPU (~80D)
+- About as hard as the sole of a running shoe
+- Good for things like bumpers or hinges
+- Still fairly easy to print
+
+ ### TPU ()
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