Use Affinity Designer to create HVAC plant using an adjustable grid system. It is as simple as using a Lego set to build 3D objects, and will fit into the existing Tridium Niagara SVG library.
When I started looking into creating HVAC plant to use in PX pages (Niagara), I opened up the SVG library to inspect some of the existing items. Mainly to get the colors that Tridium use and also to understand the layout grid angles used for air plant and ductwork which is set to 146° and Mechanical plant, like Chillers and Boilers which is set to 135°. I don't understand the reason for the difference and look somewhat odd when px pages contain plant elements of both. I suggest you don't mix them if possible!
In Affinity Designer there are features that help us when building plant items. In previous training, I have used Figma for building SVG's, which is brilliant, but the flexibility of Affinity Designer makes easy work of some of the more complex 3D type graphics.
Under the View menu, you will find the option of Grids and Axis manager, which gives us the option to set up a custom Grid. In the example below I have set the grid to 135°. With the grid set, we can start laying out objects to build up our design using the Isometric features.
Once the Isometric panel is enabled we can create 3D objects very quickly keeping to the perspectives that we have set up by our grid. The image below shows that I have the Front Plane seleted and we have a square grid. I now draw an oblong onto the grid, which snaps nicely into place.
If I changed my mind and this oblong was going to be a side panel and not a front (normally I would have to do a complicated calculation to work the adjustments to fix the side perspective). However, in Affinity we can first select the side plane, which changes the grid to our preset angle. Then select, fit to plane.
This changes the panel to fit the side plane without any fuss. Using these tools we are able to build equipment like we have a toy building block construction set, building panels as we need them.
The image below shows the finished units, which I put together for a friend who needed a wall unit for a project. Out of interest, I wanted to see how long it would take to build an indoor unit and the accompanying Outdoor unit. From start to finish, I guess it took about an hour of time on a rainy Saturday afternoon in lockdown. The only functional feature missing from these units is the animation of the fans. (Perhaps this can be added later.)