# Parametric FreeCAD Designs > Editable, printable parts with dimensions that can change without rebuilding the model from scratch. Canonical page: [Parametric FreeCAD Designs]() Project date: Apr 2026 Updated: 2026-10-14 Category: CAD & fabrication Status: Open source Tags: FreeCAD, Parametric modeling, 3D printing - **My work:** Parametric CAD and printable part design - **Example:** Magnet-mounted Fridge Cup - **Files:** FreeCAD source · 3MF · dimensioned drawing - [Get the CAD files]() ## In short I design printable parts in FreeCAD with dimensions that can change without rebuilding the model from scratch. My Fridge Cup uses editable dimensions and magnet pockets to adapt an open-topped holder to a different space or set of magnets. ![A CAD render of a tall rectangular cup with rounded edges and four magnet pockets on the back.]() The Fridge Cup model, with its rear magnet pockets visible. ## Overview I design printable parts in FreeCAD (computer-aided design, or CAD, software) with dimensions that are easy to change. The Fridge Cup is a small example: an open-topped holder that mounts to a steel surface with four magnets in its back. Its width, height, wall thickness, and magnet pockets are editable parameters (values that control the model), so the design can be adapted to a different space or set of magnets. ## Model dimensions The Fridge Cup exposes its dimensions through a FreeCAD `VarSet` (a set of named variables). The table includes fillets (rounded edges). | Parameter | Default | What it controls | | --- | --- | --- | | Length | 100 mm | Outer footprint length | | Width | 30 mm | Outer footprint width | | Depth | 75 mm | Cup height | | Thickness | 3 mm | Wall thickness | | Fillet | 5 mm | Vertical corner radius | | MagDiameter | 6.2 mm | Magnet pocket diameter | | MagThickness | 2 mm | Magnet pocket depth | | MagInset | 10 mm | Pocket inset from the corners | | Angle | 60° | Trapezoidal base angle | The top edge uses twice the main fillet value. Changing the magnet parameters resizes the pockets in the model. ## Editing the model ### Changing dimensions Open the `.FCStd` source (the editable FreeCAD file) and select the `VarSet` in the model tree. Adjust the dimensions there, recompute (rebuild the geometry from those values), and inspect the resulting geometry before exporting a new print file. ### Checking a revision Useful checks for a revision include: - Overall size changes independently from wall thickness. - Magnet dimensions match the purchased components. - Pocket placement still leaves enough material around the edges. - Fillets remain valid after changing the footprint. - The editable source is saved alongside the new export. After changing dimensions, check for failed fillets, thin walls, or pockets that break through an edge. ## Printing and assembly ### Print orientation The cup is designed to print without supports (temporary printed structures beneath overhangs), with its closed base on the build plate (the printer’s printing surface) and the opening facing upward. ### Magnets and print files Four 6 × 2 mm neodymium discs (rare-earth magnets) press into the rear pockets. The modeled pocket diameter is 6.2 mm; check the fit with your printer and magnets. The `.3mf` export (a 3D-printing file) is available for slicing (preparing printer instructions), while the source remains the place to change the design. ## Physical result and limitation The small magnets I used only just held two full-size dry-erase markers without slipping. For a heavier load, the next change would be larger or stronger magnets and resized pockets. The CAD makes that change easy, but the revised mount still needs a load test on the intended surface. ## Files and related builds The [FreeCAD repository]() contains the source, 3MF, drawing, and license. Retain the attribution and license with redistributed versions. Other examples of fitting printed geometry to real objects include the [Catan organizers]() and the [electric bicycle mounts](). Each project has its own fit and assembly constraints. My [Everyday Prints]() collection adds adjustable household and workshop parts with editable Python source and a browser customizer. My [Guitar Floor Stand]() entry covers a one-piece stand with editable FreeCAD source, a padded guitar envelope, and structural simulation checks. I built [PrintCAD Brief]() to collect dimensions, geometry notes, and fit-test history into a shareable build brief, with an STL viewer for marking model changes. ## FAQ ### Which Fridge Cup dimensions can I change? The FreeCAD VarSet exposes footprint, height, wall thickness, fillets, and magnet-pocket dimensions. Change the values, recompute, and inspect the geometry before exporting. ### Does the Fridge Cup need print supports? It is designed to print without supports, with its closed base on the build plate and its opening facing upward. ### How much did the tested magnets hold? The small magnets used in the build only just held two full-size dry-erase markers without slipping. A heavier load would need larger or stronger magnets, resized pockets, and a new load test. ## Build photos ![Gray CAD preview of the Fridge Cup with an open top and four circular magnet pockets on the mounting face.]() CAD preview of the Fridge Cup from the FreeCAD repository, showing the magnet-pocket face. ## Related reading - [Organic Topology Guitar Floor Stand]() - [Everyday Prints]() - [3dprinterverse]()