ARPen vs TDMS
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
ARPen
Create 3D drawings and models in mid-air using a marker or a custom Bluetooth pen. Explore advanced geometry creation, object manipulation, and depth visualization. Export your creations as STL files.
- Draw freehand in mid-air
- Create simple and complex geometries
- Manipulate objects in 3D space
- Explore depth visualization
- Export models as STL files
- Use marker or custom Bluetooth pen
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The ARPen application enables you to draw in mid-air. By tracking a marker, lines can be created that keep their position in the real world. Printing out a marker is all that is needed to test out this interaction. Or you can build a custom Bluetooth pen to have more options. The pen can be built using simple electronic components and machinery in your local Fab Lab. Detailed instructions are available at http://hci.ac/arpen-ios. With this app you can: - paint freehand in mid-air - create simple geometry shapes like cubes - create complex geometries using sweeps, lofts, revolutions, and merge&intersect operations - explore techniques for moving, rotating, and scaling objects in mid-air - explore different menu techniques - explore depth visualization techniques to show the position of the pen tip relative to other objects in the scene - export the sketch or model as an *.STL file This application is part of the Personal Photonics project, which is funded by the German Federal Ministry of Education and Research (BMBF) as part of their Open Photonics call. For more information, visit https://hci.rwth-aachen.de/arpen
TDMS
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■Manage measurement data using standard to determine pass/fail The measured torque and angle values are judged based on the upper and lower limits registered for each potion, and saved with adding date, time and pass/fail judgment result. ■Work information can be registered on the app or by imported in bulk with the master file. Work information such as standard values and number of spindle be easily registered on the app. Batch registration is also possible by creating and importing a master file in Excel or CSV format. ■For detecting abnormalities in early stage, automatically processed statistical data from the measured results. To detect abnormalities early stage, "N", "X-bar", "σ", "cp" and "cpk" are automatically calculated from the measurement data. ■Outputs saved measurement data and statistical data as a file The data can review in the app and also output it as an Excel or CSV file. ■Compatible with many Tohnichi Digital products It can easily establish data management system by connecting with Tohnichi product. ■Sends the portion information to be measured to the torque wrench. The registered portion information will be sent to Tohnichi digital products, it allows to perform your operation while switching the standard values according to each portion.
Screenshots
Verdict
The clearest difference is update cadence: ARPen at every 4 months against TDMS's every 26 months. On price, ads, in-app purchases and device support there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. Neither carries in-app purchases, so what you see is what you pay.
ARPen ships an update every 4 months, TDMS every 26 months. The most recent releases landed on October 9, 2026 and October 25, 2026 respectively.
| Parameter | ARPen | TDMS |
|---|---|---|
| Price | Free | Free |
| Rating | 2.5 (2 ratings) — better | — |
| Positive reviews | 50.0% of reviews | — |
| Number of ratings | 2 — better | — |
| Update frequency | Every 4 months — better | Every 26 months |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Free | — |
| Devices | iPhone, iPod | iPhone, iPad, iPod — better |
| Requires iOS | 14.2 — better | 15.0 |
| Further details — not scored | ||
| Size | 55 MB | 4 MB |
| Age rating | 4+ | 4+ |
| Developer | RWTH Aachen University | TOHNICHI MFG.CO., LTD. |
In-app purchases
ARPen
No in-app purchases
TDMS
No in-app purchases









