Dr. Luka Kovač
Emergency Physician, War Survivor, Innovator in Regenerative Medicine
MedTech for Croatia Initiative
A Detailed Guide: How to Build a 3D Bioprinter and Flesh Printer for the Healing of Soccer Players and War Veterans
Croatia has produced warriors on the battlefield and on the soccer pitch. But both leave the body broken — torn ACLs, shattered bones, burnt flesh, amputated limbs. As a doctor who has witnessed war and treated trauma, I believe it’s time Croatia leads the next medical revolution: regenerative bioprinting.
Here is my step-by-step explanation for building a 3D bioprinter and a flesh printer in a cost-effective, modular way — suitable for clinics in Zagreb, Rijeka, or even rural villages like Sinj.
🧠 1. UNDERSTANDING THE MISSION
Before the tools, we need the why:
- Soccer Players: Meniscus tears, cartilage damage, torn ligaments.
- War Veterans: Burned skin, missing muscle tissue, damaged nerves, amputated limbs.
A 3D bioprinter can print living tissue: skin, cartilage, muscle — even bone scaffolds — layer by layer using “bioinks” composed of living cells and hydrogels.
🛠️ 2. BUILDING THE 3D BIOPRINTER FRAME
Start with a cartesian 3D printer base — modify a commercial 3D printer or build your own:
Hardware Requirements:
- Frame: Aluminum V-slot extrusion (80/20 system)
- Stepper motors: NEMA 17
- Linear rails and bearings: For precision XYZ movement
- Heated build platform: Optional for temperature control
- Controller board: Arduino Mega with RAMPS 1.4 or Duet 2 WiFi
- Syringe extruder head: For bioink (replace filament extruder)
🧬 3. BIOINK EXTRUDER SYSTEM
Replace the plastic filament system with a syringe-based extrusion system:
- Syringe pump: Controlled by stepper motors
- Cooling/heating system: Peltier elements or a thermoelectric control box
- Sterile disposable cartridges: Autoclavable if possible
Use Luer lock syringes loaded with bioinks such as:
- Skin cells (keratinocytes, fibroblasts)
- Cartilage cells (chondrocytes)
- Stem cells (mesenchymal from fat or bone marrow)
🔬 4. SOFTWARE & G-CODE MODIFICATIONS
Use open-source slicing software like Cura or Repetier Host, but modify G-code commands for:
- Syringe extrusion
- Pausing between layers (to allow gelation or crosslinking)
- Multi-nozzle control (if printing multiple tissue types)
Advanced version: Use MATLAB or Python scripts to control the printer dynamically based on real-time imaging or MRI scans.
🧪 5. BIOINK FORMULAS
Each tissue requires specific bioink:
For Skin:
- Hydrogel base: Collagen + fibrin
- Cells: Keratinocytes (epidermis), fibroblasts (dermis)
- Additives: Vitamin C, growth factors (EGF, FGF)
For Cartilage:
- Hydrogel base: GelMA (gelatin methacrylate) + hyaluronic acid
- Cells: Chondrocytes or induced pluripotent stem cells (iPSCs)
For Muscle:
- Hydrogel: Fibrin + alginate
- Cells: Myoblasts (muscle progenitor cells)
For Bone:
- Scaffold material: Tricalcium phosphate or hydroxyapatite
- Cells: Osteoblasts or stem cells
💡 6. PRINTING AND CROSSLINKING
After each layer, crosslink the hydrogel to solidify it:
- Use UV light for GelMA
- Use calcium chloride bath for alginate
- Use thermal gelation for collagen
Each layer is printed layer-by-layer, mimicking the real anatomy using patient imaging (MRI or CT scan).
🏥 7. POST-PRINTING: BIOREACTOR INCUBATION
Place the printed tissue in a bioreactor:
- Controls temperature (37°C), CO₂, oxygen, and flow of nutrients
- Helps vascularize the tissue
- Can be built from aquarium components, perfusion pumps, incubator controllers
⚕️ 8. CLINICAL TRANSLATION
Once printed tissue is matured:
- Autologous grafting for burns and wounds
- Joint repair for soccer players (meniscus, cartilage patches)
- Muscle replacement for veterans
- Bone scaffolds for cranial or limb injuries
🇭🇷 9. CROATIAN LOCALIZATION
Croatia can:
- Source stem cells from patients in local clinics
- Train bioengineers from Croatian universities (Split, Zagreb)
- Partner with hospitals and veterans’ groups
- Build regional tissue banks and bioink repositories
🔧 10. COST ESTIMATE (DIY STARTER VERSION)
| Component | Cost (USD) |
|---|---|
| Frame, motors, rails | $250 |
| Controller board | $50 |
| Syringe extruder | $100 |
| Bioink materials | $500 |
| UV crosslinker | $100 |
| Bioreactor setup | $200 |
| Total | ~$1,200 |
This is a fraction of commercial systems that cost $50,000–$300,000.
👨⚕️ FINAL THOUGHTS FROM DR. KOVAČ
Croatia’s future does not lie in importing overpriced Western tech. We must build with our own hands, for our own people — for the boys who gave their legs in war and the men who gave their knees to the game.
Let this project be a new healing pilgrimage: not to Lourdes, but to a humble lab, where flesh is printed, and hope reborn.
“Kad već ne možemo vratiti prošlost, možemo barem obnoviti tijelo.”
(“If we cannot return the past, we can at least restore the body.”)
— Dr. Luka Kovač