Trial, Modify, and Follow Up
A printed device may need to be trialed before it is treated as ready for regular use. A device can look appropriate after printing but still create problems with fit, comfort, grip, attachment, cleaning, durability, or use during the intended task. This tutorial gives general guidance on how an OT may trial a printed device, gather feedback, and consider whether the next step is a slicer change, a material change, a CAD edit, collaboration, reprinting, or a different device.
Beginner Note
An OT who is new to 3D printing does not need to begin by designing a device from scratch. A beginner can start with an existing file, print the device, check the finished print, and test it with the intended task and object. Many early changes can be made in the slicer. These include scaling the device, changing print orientation, adjusting wall thickness, changing infill, or choosing a different material.
Computer-aided design (CAD) becomes more relevant when the model's shape needs to change. For example, CAD may be needed if an opening is the wrong shape, a handle does not match the client’s grasp, an edge creates pressure, or the device needs a new attachment point. If the OT lacks CAD experience, they may work with an engineer, maker, student, colleague, or 3D printing specialist.
Before the Trial
Before a device is trialed with a client, the OT or printer user may review the finished print for visible concerns. This may include cracks, loose sections, rough edges, sharp areas, weak layer lines, poor attachment points, or parts that move differently than expected. If the device connects to another object, the fit with that object can be checked before the device is used during an activity with a patient.
The trial should match the actual task and object as closely as possible. A utensil holder can be checked with the utensil the client plans to use. A zipper aid can be checked with the zipper style used on the client’s clothing, backpack, or bag. A bottle opener can be checked with the cap or bottle type that the patient plans to use it with. These checks give the OT information that may not be clear from the file page, photos, or finished print.
What the OT May Check During Use
During a trial, the OT may observe how the client uses the device during the intended activity. This may include how the client positions the device, whether the device stays in place, whether the device changes the movement required for the task, and whether the client appears comfortable using it.
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Fit is too loose or too tight
Grip surface is difficult to hold
Device slips during the activity
Edges create pressure or discomfort
Device is too rigid or too flexible for the task
Attachment point does not match the object
Device blocks part of the task
Device changes the movement pattern in a way that makes the task harder
Client needs more setup assistance than expected
Device shows unintended bending, cracking, or weak areas during use
The OT may also consider posture, force used during the task, setup needs, and feedback during the activity. A device may complete the task during one trial but still be a poor match if it creates discomfort, requires awkward positioning, or adds setup steps the client cannot manage in the intended setting.
Naming the Problem Before Changing the File
The OT may need to identify the specific issue before changing the file or print settings. A general statement such as “it does not work” does not give enough direction for a useful change. The concern can be described in terms of fit, comfort, movement, attachment, durability, setup, cleaning, or task match.
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If the device fits the object but feels weak, the issue may relate to material, print orientation, wall thickness, infill, or layer adhesion.
If the device is the right shape but too large or too small, the issue may relate to scale.
If the device fits in one direction but blocks part of the task, the issue may relate to device orientation, object placement, or the model shape.
If the device does not fit the intended object, the issue may relate to object size, object shape, or the opening in the model.
Naming the problem makes the next step easier to choose. Some issues belong in the slicer. Some belong in material selection. Some require CAD. Some mean the current device is not the right option for the client, task, or setting.
Slicer and Print Setting Changes
Slicer changes affect the print instructions sent to the printer. They do not change the shape of the original model file. These changes may be considered when the general shape of the device is appropriate, but the printed result needs a different size, stiffness, surface quality, strength, or print setup.
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Scaling the device larger or smaller
Changing material from PLA to PETG or TPU
Changing print orientation
Increasing wall thickness
Changing infill
Adding or removing supports
Adjusting layer height
Reprinting with a different orientation
A slicer change is often the first place to start when the model shape is acceptable. For example, a device that is slightly too small may be scaled in the slicer before trying CAD. A device that breaks along layer lines may need a different print orientation or more wall thickness. A device that is too rigid for the task may need a different material, such as TPU, if the printer and device design allow it.
(Computer-Aided Design) CAD Changes
CAD changes alter the model geometry. This means the shape of the device changes before it is sliced and printed. CAD may be needed when the device needs a different opening size, handle shape, angle, grip area, attachment point, thickness, or contour.
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Widening an opening so the device fits around a larger object
Changing a handle shape to better match the client’s grasp
Adding texture or ridges to change the grip surface
Rounding an edge that creates pressure
Changing the angle of a part
Adding a hole, slot, strap path, or attachment point
Removing part of the model that blocks the task
Scaling in the slicer changes the size of the whole printed object. Editing in CAD can change one part of the object while leaving the rest alone. For example, scaling a utensil holder makes the entire holder larger or smaller. Editing the file in CAD could widen only the utensil opening while keeping the grip area the same size.
Working With Another Person
An OT does not need to complete advanced CAD edits independently to be part of the modification process. Depending on the setting, the OT may collaborate with someone who has more design or printing experience. This may include an engineer, maker, student, colleague, or 3D printing specialist. Clear information helps the person modifying the file understand what needs to change and why.
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The task the device is meant to support
The object the device needs to fit
The part of the device that did not work during the trial
Measurements that affect fit
Photos of the object or device, when allowed
Material used for the first print
Printer or slicer limits
Cleaning needs
Safety concerns
Client feedback related to use
Identifying information should be handled according to the setting’s privacy policies and applicable requirements. In many cases, the person modifying the file does not need private client details to change a handle size, widen an opening, or adjust an attachment point.
Follow Up and Next Steps
The next step depends on the trial, the setting, the client’s feedback, and the OT’s clinical judgment. If the device appears to fit, feels comfortable, stays in place, and matches the intended task, the OT may continue monitoring use over time. If there is a clear concern, the OT may consider whether the issue relates to slicer settings, material choice, print settings, CAD design, or device selection.
The process may lead to another print, another trial, or a different device. A printed device does not need to be forced into use if it does not match the client, activity, or setting. The OT may stop use and consider another option if the device causes pain, skin irritation, unsafe movement, unstable attachment, sharp contact, or visible part failure during use.
Educational Use Note
This tutorial is for general educational purposes. Device use, modification, documentation, client instruction, privacy, and follow-up should follow the OT’s role, setting, supervision requirements, facility policies, and applicable safety rules.