December 12, 2025
Description
Get your electrical boxes perfectly flush, even when the framing isn’t.
Warning: Users must check local electrical codes to ensure compliance. Use at your own risk. The creator assumes no liability for improper installation, damage, or injury.
Electrical boxes are rarely perfectly installed. Studs can be slightly crooked, boxes may sit too deep, or the top and bottom may not be level. Traditional fixes involve stacking one or more spacer rings, or attempt to remount boxes—sometimes requiring drywall / sheetrock patching.
This Single Gang Box Extender and Leveler is designed for Carlton single-gang boxes (PN: B118A, B120A, B122A), commonly found at big-box stores, and provides a smarter alternative. Unlike standard extenders, it offers:
Common dimensions are included in the provided .3mf file; custom dimensions are available upon request.
It’s designed to be 3D-printed using UL94 V-0 rated filament. Printing profiles for PETG and ABS are provided, and recommended filaments include:
The key measurements are:
Bottom/Top/Left/Right are all relative - as long as you align your measurement with the model definitions of C1, C2, C3, things should work out fine. See images for more information on these dimensions.
These measurements can be taken with a set of calipers (depth). Ensure that:
The .3mf file currently includes the following model variants, each on a separate plate:
| Model | C1 | C2 | C3 |
|---|---|---|---|
| 1/8 Inch Flat | 0.125in | ||
| 1/4 Inch Flat | 0.25in | ||
| 3/8 Inch Flat | 0.375in | ||
| 1/2 Inch Flat | 0.5in | ||
| 3/4 Inch Flat | 0.75in | ||
| 1/8 - 1/4 LR Pitched | 0.125in | 0.125in | 0.25in |
| 1/8 - 1/4 TB Pitched | 0.125in | 0.25in | 0.125in |
If the dimensions you require are not available, let me know and I can get them uploaded.
To install, slip the FlushFrame over the Carlton box. The fit will be snug - the safety ring is sized such that a little bit of force/manipulation will be required to get full engagement. This is normal (and desired).
If installing on a box where a device is already present, ensure that the branch circuit is de-energized prior to beginning install.
License:
Standard Digital File License