Chrome Extension – Amazon Price Drop Percentage

Chrome Web Store promotional image

Chrome Web Store promotional image


This extension illustrates, via colour highlights, the extent of a price drop on and

The extension works in the background and requires no user intervention. The extension is always on and alters the default price change alert box as the page loads. To turn it off, go to chrome://extensions and uncheck “Enabled” next to the title of the extension.

Amazon Price Drop Percentage is not an official extension from, Inc.



Fritzing Parts – Seventh Set

To mark the occasion of 50,000 downloads of parts from the previous six sets, I’ve made a seventh set of Fritzing parts. The first set of parts, along with details about Fritzing and about part creation, can be found here. All sets can be found under the ‘fritzing’ tag here. As with the previous sets, these are generally parts that I’ve needed for my own projects.

The group of Fritzing parts.

The group of Fritzing parts.


The group of Fritzing parts, numbered.

The group of Fritzing parts, numbered.

The parts are as follows:

  1. LMD18200T
  2. TCS3200D
  3. Nano Pi NEO
  4. RCWL-0516
  5. CCS811
  6. AK-SI7021
  7. TEMT6000
  8. MyoWare LED Shield
  9. RFP-611
  10. RFP-602

Since the Fritzing parts repository ( is no longer available for sharing parts, they will be posted here instead.   If you’d like to make a request for the next set, please leave the following details in the comment section below:

  1. The name of the board/module
  2. The outside dimensions in millimeters
  3. Details about each pin (i.e. name — e.g. VCC, GND, SDA)
  4. An image of it at a reasonable resolution (and as close to parallel to the image plane as possible)

Bronica ETRSi Battery Compartment Cover Replacement Part

The Bronica ETR series were 6×4.5 film SLR medium format cameras manufactured by Zenza Bronica in Japan from 1976 to 2004. The series consisted of the original ETR (January 1976), the ETRC (October 1977), the ETRS (January 1979), the ETR-C (January 1979), modified ETRS (July 1982), and the ETRSi (October 1989) (Gonzalez, 2016). Production of the ETRSi ended in December 2004; full technical support for the ETRSi ended seven years later, in December 2011.

The ETRSi incorporated a number of changes over the preceding ETRS, namely improvements in the focusing screens, shutter speed dial, and in sound and light-deadening material in the interior of the camera (Gonzalez, 2016). One other relevant change was the enlargement of the battery cover over that of the ETRS (#2912) to that of the SQ-A (#1912) (Gonzalez, 2016).

The battery cover in place on the bottom of the Bronica ETRSi

The battery cover in place on the bottom of the Bronica ETRSi

As is often the case, various parts of such a camera system can go missing – the eyepiece, the winding lever, the battery cover, and so forth. In the case of the battery cover, replacements are hard to find. The only other (efficient) way to obtain a replacement battery cover would be to buy a broken ETRSi camera body. Though this is useful from a long-term repair perspective, it is not entirely feasible if just the battery cover is needed. The intent here was to create a 3D model of a ETRSi battery cover in order to allow for 3D printing of replacements.

FreeCAD screenshot of battery cover 3D model

FreeCAD screenshot of battery cover 3D model

Using the original part as a guide, I constructed a 3D model using FreeCAD. I decided to keep it close to the original part in terms of design. That said, the grip/groove pattern was changed slightly, in order to make it easier to shift over. Because of the lack of a finish on the replacement battery cover, it is easier to remove from the camera body, as compared to the original battery cover (due to the rougher, as opposed to smooth, surface finish).

The part was test printed by Sculpteo (Paris, France). The total cost, with shipping, ended up being €6.00 (~$9.00 CAD; ~$7.25 USD).

The materials and related characteristics were:

Process: Multijet Fusion
Material: Nylon PA12 (Black)
Finish: Raw

Original and replacement battery cover

Original (bottom) and replacement (top) battery cover

Part Download

The part can be downloaded from Thingiverse.


Gonzalez, D. (2016). Bronica medium format cameras. Retrieved from