Introduction: Froggy: the 3D Printed Ball-jointed Frog Doll

About: British techie moved to Texas in 2013. Now a full time, freelance artist. Interested in articulation and assemblies. Fan of support-free models. John Joseph Merlin is my hero.

This is Froggy - my first ball-jointed doll!

Unlike my other models, some parts of this frog doll require the use of supports and a brim. He is strung together with two types of elasticated cord and some parts require gluing. Stringing allows him to hold a wide range of poses.

Froggy can be downloaded from:


Froggy was a featured model on both Thingiverse and Youmagine. He also had an article written about him:

Step 1: Tools

To make this doll, you will need:

1) Elasticated cord: up to 3mm in diameter. Available from most hobby stores in the "kids' craft" section.

2) Elasticated string: Mine is roughly 1.2mm in diameter and available from hobby stores and anywhere that has sewing supplies.

3) Glue capable of sticking plastic (or whatever material you are printing with) together.

4) Tools:

i) Threading the cord through the pieces can be tricky, so I recommend the use of a hemostat to help hold cord in place whilst threading and to pull cord through holes. However, small pliers and bulldog clips can work just as well.

ii) A crochet hook can help pull cord through holes and is available cheaply from hobby stores or anywhere which sells sewing supplies.

iii) A small pair of scissors to cut cord and string as needed.

Now I have a better idea of what I am doing, future dolls may be entirely support free, but I'm not promising anything...

Step 2: Printing Froggy

Unlike my other models, some parts of this frog doll require the use of supports and a brim (I used 10mm). This was sliced using Slic3r 1.2.6 and printed using RepetierHost v1.06 on an Ordbot Hadron. I have not tested with any other slicer, printing software or printer.

All parts were printed with a layer height of .2mm and an infill of 5% on a cold bed using Elmer's glue as an adherent. However, user feedback has suggested 10% infill may be a better option to avoid any possible holes for pieces like the head and feet.

I strongly advise measuring the diameter of your filament, as over or under extrusion could result in the model parts not fitting together properly.

Please note that: froggy_assembled_FOR_REF_ONLY.stl is simply a decimated combination for assembly reference and not for printing.

The following is a break down of how I printed the parts and what worked for me. Of course, you may have better ways of doing things and all feedback is welcome. It was suggested I upload a combined and decimated version of the finger files. You can now print a finger at a time and it should take far less time to slice.

Parts that do not require supports:


I used a brim when printing all of these, although you could probably print the feet, neck ball, brace and neck threads without.

Parts that use slic3r default auto detect support setting (overhang angle set to 0):


Advise the use of a brim.

These parts needed more support (I used an overhang angle of 45 degrees):


Advise the use of a brim.

Items to be printed in the following quantities:

right_foot.stl x 1

left_foot.stl x 1

neck_ball.stl x 1

neck_threads.stl x 1

hip_joint_upper.stl x 2

hip_joint_lower.stl x 2

finger_lower.stl x 8

finger_middle.stl x 8

finger_top.stl x 8

brace.stl x 1

head.stl x 1

body.stl x 1

forearm.stl x 2

left_hand.stl x 1

right_hand.stl x 1

chest.stl x 1

lower_leg.stl x 2

knee.stl x 2

left_upper_arm.stl x 1

right_upper_arm.stl x 1

eyeball.stl x 2

eyeball_pupil.stl x 2

left_thigh.stl x 1

right_thigh.stl x 1

hand_ball.stl x 2

elbow.stl x 2

Step 3: Part Assembly: Eyes

You will need prints of:

eyeball.stl x 2
eyeball_pupil.stl x 2

Simply glue the pupil on to the flat top of the eyeball model. The top is the flat area furthest away from the holes.

Step 4: Part Assembly: Neck Threads and Neck Ball

The neck ball allows Froggy to twist and bend his head and neck. This has to be assembled so it can screw into the head (being able to remove this allows you to thread the head. otherwise you'd have real problems).

You need:

Glue these together as shown in the picture. There is a small mark near the top of the neck threads. Make sure this lines up with the hole for the cord as shown, otherwise the neck ball will not line up when probably screwed into the head.

Step 5: Part Assembly: the Body and the Brace

You will need the following:


Glue these two together. Use the marker on the brace as a guide to line up the models. The marker must be front top center.

Step 6: Part Assembly: Hip Joints

You will need the following:


Glue together as shown.

Step 7: Stringing Froggy Diagrams

How you string this doll will depend on what you want to do with him. If you want the frog to hold a pose and not be "floppy", then the tighter you will need to string him. Bear in mind though, if you string him too tight, he'll simply "kick" and won't be able to hold his limbs straight. It boils down to practice and you may end up restringing your doll a number of times before you reach a point where you are happy. I'm not an experienced doll maker, so this is the best advice I can offer.

I can recommend from what experience I have had, to use careful knotting, so the strings don't come undone. I found a singly slipped square (or reef) knot worked well for me:

The eyes, hands and feet are strung using a the elastic string as it allowed me to use smaller pieces and for those pieces to have some independent of the main body. I have included two stringing diagrams which should be used as guides. The thicker lines indicate that the 3mm cord should be used. The thin red lines indicate that the elastic string should be used.

Step 8: Stringing Froggy: Eyes and Head

This uses the elasticated string.

Ensure all support material is removed from the eye socket. The eye in the socket is a tight fit and any excess material is going to cause a problem. A smooth surface will improve rotation, so sand down if needed.

Thread one eye first, having one thread go out the opposite socket and the other through the neck hole. You will need to push the eye into the socket. Once this is done repeat for the other side and knot securely - but do not knot around the "loop" in the head. - knot above it. Trim excess string.

Step 9: Stringing Froggy: Arms and Chest

This uses the 3mm elasticated cord.

Each forearm has a loop in it. Start by stringing the forearm of your choice, allowing enough cord so it can go through one arm, through the chest, down the second arm and back up through the chest where you will knot it. Take care not to let the cord twist and you'll want to string this pretty tight if you want you frog it hold his arms up.

Step 10: Stringing Froggy: Hands

This uses the 1mm elastic string.

This are somewhat awkward to do I'm afraid. String them two fingers at a time, securing each with a knot. Once the fingers are finshed, glue the hand_ball.stl to the hand. The palm of each hand has a circle on it to act as an indicator. Once the hands are complete, they can be string onto the arms with 1mm elastic string, using the loop inside the forearm. I found the easist way to do this, is to pull the strung forearm away from the elbow and thread the string through. It can then be tied to the loop of the hand ball.

Step 11: Stringing Froggy: Legs and Feet

These are strung together in the same way the arms and hands are. If you want your frog to stand, then you'll need to string his legs reasonably tight. As per the diagram, use the loop of the brace and tie your knot there.

Step 12: Stringing Froggy: the Head and Body

Thread 3mm cord through the loop in the head and then screw in the assembled neck ball, making sure the ends of the cord go through the hole. Thread through the chest, making sure the head cords go in front of the cords for the arms.

It is then a case of tying this to the frog body by knotting the cord around the brace in the body. Unfortunately it was too difficult to take a picture that would be of much use, but the diagrams should help you. You need to make sure the neck is nicely settled into the cavity in the chest otherwise his head will tend to pop up. Once he is assembled, you'll need to twist and pull his joints into place.

Please contact me if you have any questions and enjoy your doll:-)