college of engineering white

Group 5: Ball Pit


The Kids First Pediatric Therapies center in Livingston, TN uses fun and engaging methods to aid physical therapy, speech therapy, and occupational therapy for children and adolescents. The current ball pit is made from flimsy plastic material and has no real entrance method apart from lifting a child in and out. Our goal is to provide them with a sturdy, functional, and ergonomic ball pit that children from the age of 1-10 can enjoy. We would also like to incorporate a feature that makes it easier to sanitize the ball pit after use, due to the pandemic.

Jacob Foster Jared Bennet Andrew Henson Ali Khoshnow

Problem Statement

The current ball pit at the therapy center is a “DIY” structure that can be improved in many ways. Not only is the ball pit small, but it is inaccessible to children without the assistance of a clinic worker lifting them in and out. An improved ball pit that is bigger, more durable, and more functional (in terms of accessibility) is required.

Design Specifications

– Ease of access in and out of the ball pit

– Ease of access if child needs assistance (drop gate)

– Overall structure strength and durability

– Easily be able to remove balls

Background Research

Many prebuilt ball pits are made of fairly weak wire frames with mesh walls. This is definitely not up to the specification we need. The allowed size of the ball pit is also rather unique, therefore buying a ball pit with offset dimensions would not be a good optimization of the clinic’s floorspace.

Concept Design 1

The first and concept that we chose to build features a large rectangular pit with an offset entrance to keep the plastic balls from spilling over. There is a foldable gate running along the width of the ball pit to assist lifting children in and out if necessary. This design also features a small gate at the bottom of the side to empty the ball pit for easy sanitation. The underside of the offset entrance is left open for storage also.

Concept Design 2

This design features a drop in slide that can be removed if needed. The idea of using a slide to enter the ball pit was discussed as slides are already used often in therapy. However, using a slide would interfere with the area inside the ball pit. The slide would be difficult to replace when removed because the plastic balls would cover the floor-area that the slide needed to cover.


Concept Design 3

Concept design 3 features a padded cutout that the children can jump through. The design is fairly basic and does not integrate any features to aid the removal of the plastic balls.

Selected Concept Design

We decided to continue developing our concept design 1, which features the folding gate, ball pit trapdoor, and offset entrance. This design fulfilled all of the requirements requested by the clinic.

Decision Matrix

Overview of Selected Design

Our selected design features a large area that the children can use, an elevated entrance to keep the plastic balls from falling out, and the gates that aid the adults when cleaning or assisting a child into the ball pit

Engineering Analysis 1

The stress analysis of a 1″ aluminum tube over longest section of tubing. This would be the area of greatest deflection when loaded. The load was assumed as a 220 pound adult pressing down on the bar. The final material used for the frame was 1″ T-slot aluminum, which has greater bending resistance than the aluminum tubing.

Bill of Materials

Document Fabrication Process

The plastic sheets arrived in sheets that were rectangular with the dimensions of 96″ by 48″

The first step was to mark out each piece we needed to cut out and mark it on our ball pit sketch.

When the aluminum railing was ordered, they also needed to be cut to size. The plastic sheeting was inserted into the channels in the square aluminum and the frame enclosed the sheets. There are many different brackets used to fasten the frame together in the corners and joints.

After the ball pit was built, the foam padding was added to the stairs and upper edge to prevent injury.

Testing Results

After completion of the ball pit, we needed to cover any hard edges that a child could injure themselves on. The foam padding was added to the areas that we believed were in areas that would have heavy traffic while in use. Inserts that cover the exposed T slot aluminum has also been added to avoid any injury.

Completed Design Photos

Instructions for Safe Use

Both the gate and trapdoor are to be used by the adult staff at the clinic. If needed to lift a child in and out of the ball pit use the drop gate to reduce the wall height, reducing the vertical distance and effort required to do so. When sanitizing the ball pit, use the trapdoor and coral the plastic balls through it into a container or bag of your choice.


2021 Spring