An idea or a sketch
Develop the shape, size, and features around how it will be used. Useful for new parts, accessories, and early product prototypes.
DESIGN ON DEMANDNEW JERSEY / NORTHEAST
Custom 3D CAD
Design & Modeling
It starts with “what if?”
We work out the shape.
DDA develops 3D CAD models and technical drawings for custom parts, prototypes, and replacement components. Start with an idea, sketch, measurements, or an existing object. Take the design files to your own fabricator, or have us 3D print the part.
2-inch telescope focuser capSee the part in use ↓
Discuss your design
A sketch, a sample, or a description is enough to start.
Custom part designReverse engineering2D drawingsDesign for 3D printing
YOU DO NOT NEED A FINISHED FILE
What do you
have to work with?
The starting point changes the work. The goal stays the same: a design that does the job you need.
Reverse engineering an existing part
Measure and reconstruct an existing component, then discuss the changes needed. Useful for replacement parts, adapters, and discontinued pieces.
A design that needs work
Review an existing model or drawing for the next step: a different fit, a revised feature, or a version intended for 3D printing. File compatibility is checked first.
FROM AN EXISTING OBJECT
Where 3D scanning helps.
Some shapes are difficult to capture with a few measurements. 3D scanning can provide surface geometry to use as a reference when reconstructing a part in CAD.
A scan is not automatically an editable CAD model. Reconstruction and checks of critical dimensions may still be needed. For simple geometric parts, direct measurement may be the more practical starting point.
DDA WORKSHOP PROJECT / TELESCOPE ACCESSORY
A 2-inch cap.
A fit worth checking.
A custom cap for the 2-inch Crayford focuser on a telescope. The project moved from a CAD model and drawing to a printed part, with revisions informed by checks on the actual focuser.
ON THE TELESCOPE
THE PRINTED PART
The fit check changed the design.
Early fit checks showed that the initial dimensions needed revision. The model was updated and reprinted over several iterations before arriving at the cap shown on the telescope.
The useful lesson: a nominal 2-inch opening is a starting point. The actual interface and the printed result still need to be checked.
See the dimensioned drawing MODEL → DRAWING → PRINT → FIT CHECK
The drawing records the cap’s geometry, including its radii, heights, flange, and slots. The model defines the shape; the physical fit check shows where it needs refinement.
Need only the design? That is a complete project too. We can discuss a handoff for your own equipment or another fabricator.
WHAT MAKES THE DESIGN WORK
A hole is a feature.
A good fit is a decision.
CAD defines the geometry. The useful work is deciding what that geometry needs to do.
What does it meet?
A shaft, fastener, mating part, or available space. Measurements at these interfaces matter more than a photo of the overall shape.
What does it do?
Locate, hold, protect, slide, or flex. Load, movement, heat, and wear help determine the features and material worth considering.
CAD design for 3D printing and fabrication
Wall thickness, orientation, clearances, and assembly can change with the process. A design intended for 3D printing needs that context from the start.
PLAN THE HANDOFF
What happens
after the design?
Choose the next step to see what to discuss. The deliverables, formats, and revision scope are agreed before work begins.
FOR A PHYSICAL PROTOTYPE
A model for the intended print process.
Discuss the printer or printing service, material, quantity, and what the first part needs to demonstrate. A print tests only the conditions you actually check.
- File to discuss
- A mesh export such as STL, with units and scale confirmed.
- Next decision
- Have DDA print it, or use your own equipment.
- Worth checking
- Fit, clearances, assembly, and the purpose of the prototype.
FOR ANOTHER FABRICATOR
A handoff the receiving shop can use.
Ask the shop which formats and drawing details it needs before the design is finalized. The manufacturing process and shop requirements shape the handoff.
- Files to discuss
- A solid exchange format such as STEP, plus a dimensioned PDF drawing where needed.
- Next decision
- Identify critical dimensions, material requirements, and the chosen process.
- Worth checking
- Shop acceptance of the files and any required tolerances.
FOR THE NEXT REVISION
Plan for the changes you expect.
If the part is still evolving, identify the dimensions or features likely to change. Discuss source-file delivery and software compatibility alongside the exported model.
- Files to discuss
- The editable source model and useful exchange files, subject to agreed scope.
- Next decision
- Define the review points and revisions included in the project.
- Worth checking
- A STEP or STL export may not preserve the original feature history.
FROM FIRST CONVERSATION TO FIRST VERSION
Agree on the job.
Then draw it.
Design time depends on the geometry, the information available, and the decisions still to be made. Printing and revisions need a clear scope too.
- 01
Define the useful outcome
What must the part do? What does it fit? What files, samples, or measurements do you have?
- 02
Set the scope and handoff
Discuss design work, deliverables, reviews, cost, and timing. Identify missing measurements before they become assumptions.
- 03
Review, then take the next step
Review the design against the agreed requirements. If a prototype is included, use it to inform any agreed revisions.
CAD DESIGN / PRACTICAL ANSWERS
Before we
open the file.
Can you create a CAD model from a sketch or idea?
Yes. A sketch or description is enough to begin the conversation. To develop the model, we work out the dimensions, intended use, mating parts, and other requirements needed for the agreed design.
Can you reverse engineer an existing part?
We can assess an existing component for measurement and CAD reconstruction. Access to the part, its condition, and the accuracy required determine the approach. Photos help with an initial review; they do not establish every dimension.
Do I need 3D scanning to recreate a part?
Not always. A simple part may be modeled from measured dimensions. Scanning can help capture more complex surfaces, but the resulting surface data may still need CAD reconstruction and checks of critical dimensions. We can discuss which approach fits the object and the result you need.
Do I have to order 3D printing as well?
No. You can commission design work on its own. Tell us whether you will use the files yourself or send them to another fabricator so we can agree on a suitable handoff.
What CAD files and drawings will I receive?
The deliverables are agreed for your project. Discuss whether you need a 3D model, print file, editable source model, or dimensioned drawing, and tell us which software or fabricator will use them. Different file types preserve different information.
Can you modify an STL or an existing CAD file?
We can review the file and the change you need. A mesh such as STL does not contain the same design information as an editable CAD model. Some changes may require rebuilding geometry rather than adjusting an original feature.
How much does custom CAD design cost?
Cost depends on complexity, the information supplied, required drawings and file formats, and the review or revision scope. Share what you need and any budget or deadline. We discuss scope, cost, and timing before work begins.
Can we work together if I am outside New Jersey?
Yes. DDA supports clients in New Jersey, New York, Pennsylvania, Delaware, and across the Northeast. Design discussions and file delivery can often be handled remotely. Projects involving an existing object may require shipping or arranging access for measurement.
LET’S LOOK AT THE IDEA
What needs
to take shape?
Tell us what it should do and what you have so far.
A useful first message
- What you want the part or design to do
- A sketch, photo, sample, or existing file you can share
- What it needs to fit, and any known dimensions
- Whether you need files, drawings, or a printed part
- Your location and any deadline that matters
Missing details? Start with what you know.