ProjBox Utility

The ProjBox Utility is a Windows or Raspberry Pi utility for generating electronic project enclosures. While these can always be drawn from scratch in a CAD program a simple generator may be more convenient. That is especially true if you stick to some standardized aspects.

There are many community designs for project boxes that try to mimic commercial cast boxes. One reason not to just copy is that cast boxes are designed with sloping walls so as to be more easily removed from molds. A 3D printed box can and should be designed with perfectly vertical walls. Cast boxes also usually have screw posts for the cover extending all the way to the base. They could not be made any other way. A 3D printed box can, with care, be designed to have "hanging posts" just at the top of the box. Also, a custom 3D printed box can have hot threaded inserts and machines screws instead of self-tapping screws.

Example

A design for a box is written as an .ini file with various parameters. For a simple case of "I need a box W x D x H with a hole on each end" the design is short.

[usbtypec] type=hole diameter=3.3 xstretch=5.9 [biphase] type=hole diameter=6.5 [corner] type=post merged=yes outer=8 inner=4.5 inset=6.5 relief=2 fill=5 slope=30 [project] type=box width=75 depth=50 height=30 radius=6 walls=2 base=2 inside=corner left=usbtypec right=biphase

One of the advantages of this approach is that the design is all visible and easily modified. You miscalculated something and it has to be wider? That's a simple text edit, a fraction of a second to generate the STL and a quick preview on your favorite software. You need to mount a PCB in the inside? Simple things are simple but there are ways to do complicated things too. In this case you just add/modify.

[pcb] type=post xspan=40 yspan=25 outer=8 inner=4.5 height=5 ... inside=corner pcb

Posts

There are five styles of posts:

Solid cylindrical post → outer
Solid cylindrical post with stud on top → outer, inner, stud
Cylindrical post with through hole → outer, inner
Cylindrical post with through hole merged into adjacent walls → outer, inner, merged=yes
Cylindrical post with through hole merged into adjacent walls and without lower section → outer, inner, merged=yes, clear

The slope parameter specifies the angle of the underside for hanging posts. slope=0 will be flat, but print very sloppily. slope=45 will be safe on almost all printers. slope=30 is a reasonable compromise.

Posts by default are a set of four specified by two different ways. If you specify with inset the posts are spaced from the inside corners. This is useful if you might resize the box or copy the configuration for other size boxes. The other way is by specifying width and height. This will give you a rectangle of posts centered in the box. Of course you can position this with xshift and yshift.

For a continuous post specify height. If you specify relief that will reference the height to the top of the box. This will make it more easily resizable.

Name	Type	Description
type	type	“post”
inset	length	distance from inside to post
xspan	length	X dimension of dual or quad layout
yspan	length	Y dimension of dual or quad layout
xshift	offset	position offset in X direction
yshift	offset	position offset in Y direction
outer	length	outer diameter of post
inner	length	inner diameter of hole in post
height	length	height of post or box
relief	length	distance from top of box to post
fill	length	distance from top to bottom of hanging post
clear	length	distance from bottom of hanging post to base
slope	angle	angle of bottom of hanging post in degrees
stud	length	length of stud on top of post
merged	bool	whether the post extends to be part of the wall

Holes

There are four styles of holes:

Round → diameter
Flatted → diameter, flat
Stretched → diameter, xstretch, ystretch
Rectangular → width, height

Holes are by default centered in the middle of a flat section of wall. Of course you can position them with xshift and yshift. If you specify more than one hole in a side that side will first be divided into equal sections. The individual holes will be centered in each section. A common adjustment is to specify xshift=5 for the left hole and xshift=-5 for the right hole. This will nudge the two closer. When configuring for multiple holes it may be more convenient to divide a wall into unequal sections. For instance, with three holes you might want to make the first and third sections bigger. You can do that by increasing their "weight", weight=1.5.

Name	Type	Description
type	type	“hole”
inset	length	distance from inside to hole
xspan	length	X dimension of dual or quad layout
yspan	length	Y dimension of dual or quad layout
xshift	offset	position offset in X direction
yshift	offset	position offset in Y direction
diameter	length	diameter of round hole
flat	length	amount that a round hole is flattened
xstretch	length	elongation of hole in X direction
ystretch	length	elongation of hole in Y direction
width	length	width of rectangle hole
height	length	height of rectangle hole
bevel	length	bevel or countersink distance each side
align	align	left, right, top, bottom alignment
weight	weight	relative share when dividing a face

Panes

A pane is a container for holes. Since holes are normally distributed left to right along a wall there needs to be a container for vertical organization. A pane can contain a pane, in which case its contents are organized horizontally.

Name	Type	Description
type	type	“pane”
face	name	holes in the pane
weight	weight	relative share when dividing a face

Blocks

Blocks are reference objects, like PCBs. You can enable them for viewing or disable them for slicing.

Name	Type	Description
type	type	“block”
width	length	width of block
depth	length	depth of block
height	length	height of block
xshift	offset	position offset in X direction
yshift	offset	position offset in Y direction
zshift	offset	position offset in Z direction

Boxes

A box is the basic top-level unit. You can have more than one in an .ini file. Each will generate an .stl file.

Name	Type	Description
type	type	“box”
width	length	width of box
depth	length	depth of box
height	length	height of box
radius	length	outside radius of corner of box
base	length	thickness of bottom side
walls	length	thickness of walls
inside	name	holes and posts on the bottom side
front	name	holes in the front side
right	name	holes in the right side
back	name	holes in the back side
left	name	holes in the left side
blocks	name	blocks to be added

Covers

A cover is an optional top-level object. Holes specified with inset will work properly in the corners.

Name	Type	Description
type	type	“cover”
width	length	width of cover
depth	length	depth of cover
radius	length	outside radius of corner of cover
base	length	thickness of cover
face	name	holes and posts on the surface

Download projbox.exe for Windows.

Download projbox for Raspberry Pi.