A Custom Bracket Prototype Example That Fits

A bracket can be only 80 mm long and still decide whether an installation looks finished or improvised. This custom bracket prototype example follows a common workshop problem: mounting a Meanwell-style power supply neatly beneath a desk or inside an equipment cabinet where off-the-shelf brackets do not match the hole pattern, clearance or cable exit direction.

The goal is not to print a plastic version of a steel angle and hope for the best. The goal is to make a part that locates the equipment properly, carries its expected load, leaves room for wiring and can be installed without drilling a second set of holes after the first test fit.

Start with the installation, not the CAD model

A useful bracket begins with the surrounding hardware. Measure the power supply body, its mounting-hole spacing, the available fixing surface and every point where a cable, plug, ventilation slot or screwdriver needs access. A calliper is useful, but a steel rule and a careful physical check are often just as important.

For this example, the power supply is mounted under a timber workbench. The bracket needs to hold one end of the unit while an existing enclosure supports the other end. It must clear a DC output connector that projects 18 mm from the housing, leave the ventilation openings uncovered and use two timber screws installed from below.

Those requirements immediately rule out a flat plate. The practical form is an L-shaped support with a locating lip, two elongated screw slots and a stand-off section that keeps the supply clear of the bench. This is why a custom part is often the cleaner answer. The exact problem is rarely the load alone. It is the load combined with access, cable routing and the awkward geometry around it.

Define what the bracket must and must not do

Before modelling, write down the functional boundaries. In this case, the bracket carries part of the power supply weight, prevents sideways movement and holds the unit at a consistent offset. It does not seal the supply, replace its manufacturer-approved mounting method or support a load beyond the intended installation.

That distinction matters. A printed bracket is well suited to light and moderate-duty mounting, alignment and cable-management tasks. It may not be suitable where a component is heavy, exposed to high heat, subject to sustained vibration or required to meet a particular electrical or building standard. For those jobs, a formed metal part, additional mechanical fixings or a different mounting arrangement may be the better choice.

Custom bracket prototype example: first design pass

The first model uses a 4 mm-thick vertical face, a 5 mm-thick horizontal mounting face and a 12 mm return lip to stop the power supply sliding forward. The difference in thickness is deliberate. The horizontal face sees bending between the screw locations and the supported load, so it benefits from more material. The vertical face mainly positions the unit and can remain lighter.

Two 5.5 mm-wide slots are used rather than round holes. The slots allow small adjustments if the timber screws are not perfectly centred or the bench structure is slightly out of square. They also make installation less frustrating, particularly when working overhead under a desk.

The design includes 2 mm corner fillets where the faces meet. Sharp internal corners concentrate stress and can split along print layers when a bracket is flexed. Fillets spread that load through the part while also making the finished component look more considered.

Material selection depends on where the bracket will live. PETG is a sensible starting point for many indoor brackets because it is tough, prints cleanly and copes with ordinary workshop temperatures. ASA is a better option around sunlight, warm equipment cabinets or outdoor exposure. PLA can produce a tidy prototype, but it is usually a poor final choice near heat because it can soften and creep over time.

For this part, PETG is selected for the first sample. It is not because PETG is always best. It is because the installation is indoors, away from direct sun, and the power supply has its own airflow. If the bracket sat above a reef aquarium light or near a warm enclosed driver, ASA would deserve closer consideration.

Print the part for the load path

Print orientation is part of the engineering, not a slicer afterthought. An L-bracket printed flat on one face can place layer lines across the bend, which may encourage separation when the bracket is loaded. Depending on the geometry, printing with the longest section on the bed and adding generous fillets can improve the way force travels through the layers.

For a small functional prototype, use enough perimeter walls to create a solid shell before relying on infill. Four to six walls, several top and bottom layers, and moderate infill are often more useful than high infill with thin walls. The correct settings depend on nozzle size, material and bracket shape, but the principle is consistent: build strength where the part needs it.

Avoid treating infill percentage as a strength rating. A 100 per cent-filled part with weak layer adhesion or a poor print orientation can still fail in a predictable place. A well-oriented part with thick walls, sensible radii and appropriate screw clearances usually performs better.

The first print should be a prototype, not a production commitment. Use the same material and likely print settings planned for the finished bracket so the fit test tells you something useful.

Test fit before chasing a perfect finish

The prototype reveals three issues straight away. First, the 12 mm locating lip is too close to the connector body, making it awkward to remove the plug. Second, the screw slots are positioned correctly, but the screw heads sit proud and interfere with the power supply housing. Third, the bracket leaves too little room to feed the cable through after mounting.

None of these problems are obvious from dimensions alone. CAD can show clearance, but it cannot always show how your hand approaches a plug, how a stiff cable naturally bends or how a screw head behaves against a slightly curved housing. This is the value of a physical prototype.

The revised model reduces the front lip to 8 mm, adds a shallow relief around the connector area and countersinks the mounting slots for suitable screw heads. A 6 mm cable passage is added to the rear edge. The support position stays unchanged because the test confirms the power supply is stable and the mounting face sits flat against the bench.

This is a good point to resist unnecessary refinement. Surface texture, embossed branding and decorative cut-outs can wait. If the bracket does not fit, clear the cable or allow a driver to reach the screw, those details add no value.

Check strength with a real-world test

A bracket is not proven because it survives being held in your hand. Install the revised sample using the intended screws and mounting surface, then load it in the direction it will experience in service. Watch for bending at the horizontal face, whitening or cracking around holes, movement at the fixing points and gradual deformation over time.

For this example, the power supply is fitted and left operating for several hours. The bracket is checked after initial installation and again once the setup has warmed up. The goal is to confirm that the material remains firm, the ventilation is clear and there is no contact between wiring and sharp edges.

Add a reasonable safety margin rather than designing to the exact measured weight. A bracket can be bumped during maintenance, cables can be pulled, and timber can vary in density. If there is doubt, increase the contact area, add another fixing point, use a thicker section or reconsider whether printed plastic is the right material.

Also inspect the interface, not just the printed part. A strong bracket installed with undersized screws into thin particleboard is only as dependable as the weakest connection. Good design accounts for the bench, cabinet or frame as part of the system.

Turn the prototype into a repeatable part

Once the fit and load test are right, tidy the model for repeat production. Keep mounting dimensions referenced from a single datum edge so changes do not shift unrelated features. Name key parameters clearly: body width, hole spacing, stand-off depth, slot length and lip height. That makes a future size variation faster and reduces the chance of a rushed edit creating a new interference.

It is also worth specifying the intended hardware in the product notes or installation instructions. Calling for a particular screw diameter, head type and mounting surface prevents many avoidable fit issues. The best bracket design can still disappoint if a countersunk hole is paired with a pan-head screw or if a user assumes adhesive will hold a part designed for mechanical fasteners.

At MnN Proto-Lab, this prototype-first thinking is what turns an awkward mounting task into a component with a clear purpose. A good bracket should not ask the installer to improvise around it. It should sit where it belongs, clear what it needs to clear and stay put.

When a standard bracket is nearly right, measure the last 10 mm carefully. That small mismatch is usually where the custom design earns its place.