April 1, 2026
Description
This is a Mr Potato mod for the HP Otto robot. It remixes the ultrasound/face part to add notches. Those notches can be used to attach accessories similarly to a Mr Potato. It is possible to make your own accessories using vectorial drawing software, which are typically more beginner friendly than CAD software.
Accessories are added to the face by sliding an insert into a notch. Some accessories require to remove the face to add them. This is done by removing the top of the head, and sliding the face part out of the robot.
The only required print is the potato_face.stl part. The inserts are provided so you can make your own accessories (explanation below), but I provide some accessories ready to print.
There is no restrictions on how to print the parts, and should be compatible with most filament types. Recommended nozzle size is 0.4mm. Printing multiple accessories at once is advised so that the inserts come out nicely (they can melt if the nozzle stays all the time above the piece).
It is possible to make new accessories without using CAD software. This is done by combining a a vectorial drawing software such as inkscape, and use some not well known (secret ?!) features of PrusaSlicer. All accessories for this model were made this way.
To make new accessories, the first step is to have a vectorial drawing in .svg format. Inkscape is a free and accessible tool to make such drawings.
The first step is to save the drawing into a .svg file. This is the native format for inkscape, so if you use that software, you don't need to do anything. Then import the drawing into PrusaSlicer by right clicking on the build plate, select "Add Shape"->"SVG" and then select your .svg drawing file in the file explorer.
This will import the drawing as a flat element. Adjust the height of the accessories. Most pieces should be printed at 0.8mm height. Some parts, such as arms, should be 3mm thick.
Use the split into objects if you have several accessories in the same drawing. After that, you can remove some objects to keep only the pieces you want to print. It is advised to print at least 2 pieces at once to ensure the inserts are well printed. If you have only one accessory in the drawing, this step is not needed.
Once the accessories are imported, one can adjust the size of the parts. Be careful to not change the height of the parts.
Once the accessories are imported and adjusted, it is time to import the inserts that attach the accessory to the face. Importing the inserts is done the same way as any ordinary print. Use the rotation tool to get them in the desired orientation.
There are two inserts: vertical and horizontal. The vertical insert is used to place pieces flush with a surface, such as the moustache, glasses or star. The vertical insert can be placed anywhere inside an accessory. The horizontal is designed to make parts stand upright, so it is for hats, arms, or tongue. The horizontal insert should be placed on the edge of an accessory, as shown in the picture below.
Finally, select the accessory and its insert by holding shift while left clicking on one after another. Once both are selected (both are green), right click on one of the parts, and select the "Merge" option. It will merge the two parts into one. Once merged, you can mirror a part by using Copy/Paste options (it won't work with the "Add instance" button, a.k.a big plus sign at the top), and then right clicking on the copied part and selecting "Mirror" -> "Along ... Axis" option.
Once all accessories are merged, it is time to print ! If you want to save or share the accessory, right click on it, and select the "Export as STL/OBJ..." option.
The notches are 3.7mm deep have the following dimensions:
The model's source files can be found at: https://cad.onshape.com/documents/ada0c04f7358aa28cc37da1b/w/ad395eabaf97d877402f6bf4/e/4f1f7f2fb62f9d29e4c3b918?renderMode=0&uiState=69ccc2f802fec3b241632beb
License:
Creative Commons — Attribution — Noncommercial — Share Alike
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