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Description
This is my replica of the legendary Rapala Mini Fat Rap 3 cm, designed and modeled directly from a precise 3D scan of an original Mini Fat Rap. Famous for its compact profile and tight, aggressive swimming action, the Fat Rap is a classic killer for perch, trout, chub, and other light-tackle predators. This 3D-printed version brings that exact tight wiggling presentation directly to your tackle box!
A massive amount of thought, engineering, and testing went into the physics of this ultra-compact design. Because it is so small, replicating the exact action required meticulous balancing. Through fine-tuning the internal structure, this model achieves the exact same characteristic swimming action as the original, creating a lifelike motion that predators simply cannot resist.
Design Notes
- 3D Scanned Precision: Modeled directly from a physical 3D scan of a real Rapala Mini Fat Rap 3 cm to ensure perfect proportions, a fat profile, and flawless hydrodynamics.
- Lead-Free / Component-Free Weighting: The original balsa lure weighs 4.2 grams. To make this project accessible to everyone, I wanted to design a lure that does not require adding external lead weights, which can be hard to source in the right sizes. Instead, through smart internal geometry, this replica achieves the iconic swimming action at a finished weight of 3.3 grams. It casts incredibly well on light gear and behaves perfectly in the water!
- Perfected Center of Mass: To match the original's physics without lead, a custom infill modifier has been integrated into a very precise area inside the body. This modifier is set to 20% infill and must not be changed, as it is the secret to the lure's unique balance and stability in the water.
- Integrated Brimplate Stability: Because of its tiny footprint, I have engineered a custom integrated brimplate as a support system. It completely locks the body in place during fast prints, eliminating any risk of wobble or detachment. Once the print is complete, you can easily "rock" the lure right off the plate cleanly—leaving no annoying connection points or bumps that need to be snipped or sanded off!
- Crucial Support-Free Lip Design: The diving lip has been carefully oriented so it can be printed entirely without supports, despite its organic, curved shapes. To achieve this successfully, it is pretty much a must to print the lip at a 0.08 mm layer height. This ultra-fine layer height is required to handle the steep overhangs without any flaws or print failures.
Strength & Testing
- 6.8 kg+ Load Capacity: Despite its tiny 3 cm size, this lure uses the exact same robust internal connection system as my larger models. It has been thoroughly tested to lift at least 6.8 kg with absolutely no issues. The internal structure and hardware anchor points are rock-solid and built to handle surprisingly large, hard-fighting fish.
Strength & Finishing
While this compact model has great structural integrity right off the print bed, applying a high-quality clear coat (like a 2-component epoxy or clear UV resin) will make it 100% waterproof, heavily increase its durability against sharp teeth, and give it a beautiful glass-like professional finish.
Assembly
The lure consists of two printed parts: the main body and the separate diving lip.
- Remove Stability Plate: Simply rock the lure off the integrated brimplate.
- Glue the Lip: Secure the diving lip into the body slot using a strong 5-minute epoxy or superglue.
- Prepare the Holes & Install Hardware: Install the 3 screw eyes into the prepared pilot holes. To make this step incredibly easy, I have uploaded a "Handdrill Handle" model on my MakerWorld profile. You can print it, glue a 1mm HSS drill bit inside, and use it to effortlessly pre-drill the holes before screwing the eyes firmly into place! Alternatively, you can gently heat the screw eyes with a lighter before pressing them into the plastic.
- Crucial Step - Front Screw Eye Orientation: When installing the front nose screw eye, it must be screwed in at an upward angle. The internal pilot hole is engineered to point diagonally upwards so the screw shaft completely clears and stays above the diving lip. Please check my uploaded cross-section image of the model to see exactly how the internal channel runs before you begin screwing it in!
- Clear the Eyes: Clear away any excess resin or epoxy from the screw eyes before curing so they stay completely open for your split rings.
- Rig the Hooks: Attach your split rings and hooks to the designated screw eyes.
Hardware Requirements
To fully assemble the lure and match its intended action, you will need the following hardware:
- 3x Screw Eyes: Stainless steel. 1.3 mm thread thickness, 12 mm full length, 5 mm outer eye diameter, 8 mm shaft length. (Can be bought very cheaply on sites like Temu or AliExpress).
- 2x Split Rings: Size 5 mm.
- 2x Treble Hooks: Size #12.
Important Print Profile Notice
To achieve the absolute best performance, I have uploaded two different print profiles depending on your printer and build plate size:
- Profile 1 (Recommended - Print by Object): This profile uses Print by Object enabled. This allows the printer to create the diving lip at the required 0.08 mm layer height to successfully handle the overhangs without supports, and the main body at a standard 0.2 mm layer height—all in the very same print job! You get the perfect finish on both parts without starting the printer twice.
- Profile 2 (Multi-Plate): If you have a very small build plate where Print by Object isn't ideal, use this profile. It splits the main body and the diving lip onto two separate plates so you can print them in two quick, individual runs.
Changing the internal infill modifier or wall settings will ruin the delicate balance of this ultra-light lure, so please stick to the profiles for the best results!
Tight lines!!
GoldenPants
