FreeRetrofit Kits for 3M Respirators -- common surgical masks can be used as filters in 3M 6000/7500 series respirators.
Thingiverse
53 model
Free
FreeRetrofit Micrometer Endstop Target for Taz 4/5
Thingiverse
FreeRetrofit Nozzle wiper for mounting a Lulzbot Mini style bed wiper to a Taz or other printer
Thingiverse
FreeRetrofit Matte Box Adapter
Printables
FreeRetrofitkit for quest 2 GomrVR - Halo to Elite conversion
Thingiverse
FreeGT2560_Retrofit_Case_with_Fan_Geetech_Aluminum
Thingiverse
FreeDesign8Studio Retrofit Riser Kickstand
Printables
FreeRecycling retrofit rings: separate your garbage into trash and recycling
Printables
FreeFlashforge Adventurer 5M Retrofit Minimal Enclosure with Everything else
Printables
FreePrintrbot LC Lead Screw Retrofit
Thingiverse
FreeSquash Ball Vibration Dampener Retrofit for AM8
Thingiverse
FreeLACK enclosure MMU retrofit and ventilation parts
Thingiverse
FreeSparrow Solutions - Zortrax Klipper retrofit toolhead
Printables
FreeDaVinci Jr v1.0 Retrofit_#Upgrade#Resurrection
Thingiverse
FreeBabylon 5 Mercury Class Retrofit, Nova Support MPV
Thingiverse
Freead5x plate holder retrofit
Printables
FreeTaz 4 X belt retrofit bolt on tensioner
Thingiverse
FreeUnbreakable Bar Clamp (retrofittable)
Thingiverse
FreeEnder 3 V3 SE - Creality Light Bar (Retrofit)
Printables
FreeSnapMaker J1 Front Load Spool Retrofit
Printables
FreeReplicator 2 Extruder Fan Blade Retrofit
Thingiverse
FreeHeated bed Cable pinch prevention retrofit clip for AO-10x series printers, Mendelmax, and possibly the TAZ
Thingiverse
FreeEnder 3 V3 - Creality Light Bar (Retrofit)
Thingiverse
FreeQidi X-Max : X-Carriage : V6 Retrofit
Thingiverse
FreeSnapMaker J1 Front Load Spool Retrofit
Thingiverse
FreeVASE MODE: Cherry Blossom Lamp Plastic Liner retrofit
Printables
FreeRapide Lite 200 E3D-V6 Bowden extruder retrofit
Thingiverse
FreeUltimaker 2 SKR 1.4 Raspberry Pi retrofit case without drilling
Thingiverse
FreeElegoo Centauri 2 Combo LED strip retrofit
Printables
FreeElegoo Centauri 2 Combo LED retrofit
Thingiverse
FreeBMW E46 Ashtray Control Panel retrofit
MyMiniFactory
FreeCR-10 SE Quiet Fan Mod - 5015 Blower Fan Retrofit Adapter
Thingiverse
FreeMount for BCN D25/W27/W50 Raspberry Pi 3B+ (Klipper Retrofit)
Printables
Freezero g mercury 1.1, eva 3 retrofit
Thingiverse
FreeUnbreakable Prusa Z-rod stabilizer constraint (push on, retrofittable)
Thingiverse
FreeCamera View Finder Snap Sights
Printables
FreeRetrokits RK008 Case & Stand
Printables
FreeFallout-Inspired Power Armor Zeerust Retrofuturistic 28mm
Thingiverse
FreeRatRig Vcore 3.0 Front Belt Tensioner retro fit
Printables
FreeMinigun Fallout t60 Power Armor Zeerust Retrofuturistic 28mm
Thingiverse
FreeX-01 Power Armor 28mm Fallout retrofuturistic
Thingiverse
FreeFallout Tesla X-01 Enclave Power Armor Retrofuturistic Zeerust 28mm
Thingiverse
FreeAstro Orks
MyMiniFactory
FreeThe Association of Ishtar | Steampunk and Cosmic Horror Characters
MyMiniFactory
FreeRetro-Futuristic DMC Wall Art
Printables
FreeMarty Supreme Character Figurine 3D Printable
Printables
FreeRetro Robot Figurine Sci-Fi Collectible 3D Printable
Printables
FreeSovieticus Soldier | FREE
MyMiniFactory