Restructure challenges into current and archive folders

challenges/archive/December-2025.md

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+---
+title: "December 2025: Bring Your Test Models"
+category: "challenges"
+subcategory: "2025"
+order: 202512
+description: "December 2025 challenge showcasing printer calibration prints, torture tests, and holiday ornaments."
+tags:
+  - challenge
+  - archive
+  - 2025
+  - challenge-003
+---
+
+# December 2025 Challenge: "Bring Your Test Models"
+
+This month's challenge is all about the models we use to test, tune, and calibrate our printers. Everyone has a favorite "go-to" print—whether it's a Benchy, a calibration cube, a torture test, or something unique you've found.
+
+**Bring your favorite test models to the meetup!**
+
+## Challenge Details
+
+### The Goal
+Share what test models you use and why. Do you use them for:
+- Calibrating dimensional accuracy?
+- Testing overhangs and bridging?
+- Tuning retraction settings?
+- Checking first layer adhesion?
+- Just for fun?
+
+### Submission Requirements
+- **Physical Model**: Bring your printed test model(s) to the January meetup.
+- **Explanation**: Be prepared to share *why* this is your favorite test model and what it helps you achieve.
+
+### Voting & Awards
+- **Group Vote**: The group will vote on what they think is the **Best Test Model**.
+- **Criteria**: Usefulness, uniqueness, or just plain coolness!
+
+## Timeline
+- **Challenge Announcement**: December 10, 2025 (at December meetup)
+- **Show & Tell / Voting**: January 2026 (during January meetup)
+- **Winner Announcement**: January 2026 (end of January meetup)