3d-printing/blind-cap

Blind Cap

A blank cover plate (tapa ciega) for a flush-mounted electrical wall box. Square plate with rounded corners, a hollow back cavity, and two internal screw bosses on the vertical centerline. Designed for 3D printing — the front face sits on the build plate so the cavity opens upward and prints without supports.

Parameters

Customizable Parameters

Parameter	Default	Description
outer_size	85 mm	Outer width and height of the cap (square)
corner_radius	5 mm	Radius of the rounded outer corners
total_depth	10 mm	Total depth of the cap (front face to back rim)
front_thickness	2.5 mm	Thickness of the front face
wall_thickness	2 mm	Thickness of the side walls
screw_hole_spacing	60 mm	Center-to-center distance between the two screw holes
screw_hole_diameter	3.5 mm	Through-hole diameter for the screw shank
screw_countersink_diameter	7 mm	Countersink diameter on the front face
screw_countersink_depth	1.2 mm	Countersink depth on the front face
boss_diameter	9 mm	Diameter of the internal screw bosses
front_edge_round	0.8 mm	Slight rounding applied to the visible front edge
back_edge_round	1 mm	Slight rounding applied to the rear outer edge

Keystone Jack Cradle

Optional internal cradle that snap-locks a standard keystone module (RJ45, HDMI, USB, etc.) centered in the front face. Every dimension is configurable, so the cradle can be tuned to whatever keystone you have on hand.

How it works:

• A separate front-face cutout (sized to the visible portion of the keystone face) frames the module from outside the cap.
• A larger cradle slot behind the cutout captures the keystone body. The cap's front face material around the smaller cutout stops the face flange and hides any gap.
• A latch-catch shelf protrudes inward from one long-axis wall at the back of the cradle. The cantilever latch hook compresses past this shelf during insertion, then springs out behind it and locks the keystone in place. (The shelf and slot proportions follow WALLY's keystone_solid receiver from thenewhobbyist/OpenSCAD.)
• The cradle protrudes from the back of the front face into the cap's cavity and on into the wall box behind it. The external front face of the cap is unchanged.

To install: push the keystone face-first into the cavity-side opening of the slot until the face flange seats against the back of the front face.

If your keystone doesn't fit, increase keystone_slot_width / keystone_slot_length / keystone_clearance. If the latch ends up on the wrong side, flip keystone_latch_side. If the latch doesn't lock, increase keystone_latch_shelf_protrusion (or its thickness).

Parameter	Default	Description
keystone_enabled	true	Add the keystone cradle behind the front-face cutout
keystone_face_width	14.5 mm	Front-face cutout width (visible face — short axis)
keystone_face_length	16.0 mm	Front-face cutout length (visible face — long latch-fulcrum axis)
keystone_face_offset_y	2.5 mm	Offset of the front-face cutout along Y, away from the latch shelf, so the cradle keeps material above the cutout for the latch to flex into
keystone_slot_width	15.6 mm	Cradle slot width (body cross-section, with hooks)
keystone_slot_length	23.5 mm	Cradle slot length (body cross-section, with hooks)
keystone_cradle_depth	10 mm	How far the cradle extends behind the front face
keystone_latch_shelf_protrusion	1.5 mm	How far the latch shelf protrudes into the slot
keystone_latch_shelf_thickness	3 mm	Thickness of the latch shelf in z
keystone_face_stop_protrusion	2 mm	Max protrusion of the face-stop wedge into the slot. Set to 0 to disable.
keystone_face_stop_thickness	2 mm	Slope height of the wedge in z (cavity-side slope spans this much)
keystone_face_stop_z_offset	1.5 mm	Distance from the cap front face to the bottom of the wedge — the recess at z=0..z_offset is where the latch hook seats once it has cleared the wedge. Increase to match a deeper hook on your keystone.
keystone_base_notch_depth	2 mm	Depth of a hole carved through the base lip at the latch-shelf z range, where a small chip on the keystone's non-latch side clips in. Set to 0 to disable. The base lip itself is auto-derived as the gap between the slot edge and the front-face cutout edge on the non-latch side (i.e. the cap-front-face material extended back into the cradle), so it always matches the cutout geometry.
keystone_latch_side	-1	Which long-axis end has the shelf (-1 = -Y, 1 = +Y)
keystone_rotation	0	Rotation of the keystone about the cap's Z axis, in 90° steps (0/90/180/270)
keystone_position_x	0 mm	Translate the keystone along X relative to the cap centre
keystone_position_y	0 mm	Translate the keystone along Y relative to the cap centre
keystone_clearance	0.2 mm	Print-tolerance clearance on each side of every cutout
keystone_cradle_wall	1.6 mm	Wall thickness around the slot

Defaults

The default values target a common 85×85 mm Spanish flush-box cover with a 60 mm vertical screw spacing. Adjust outer_size and screw_hole_spacing to match your specific wall box.