A simple syringe holder that mechanically synchronizes two syringes to simultaneously add and extract equal fluid volumes.

Controlled liquid exchange is a fundamental requirement for numerous biological and chemical experimental protocols. However, achieving constant-volume exchange often requires electronic syringe pumps that are cost-prohibitive and time-consuming to set up in a push-pull configuration. To address these limitations, we developed the Push2Pull syringe holder, a simple 3D-printed device that mechanically synchronizes two syringes to simultaneously add and extract equal fluid volumes. This device is compatible with standard disposable syringes from 1 to 60 mL in size and operates without electricity or additional hardware, making it ideal for both laboratory and field settings. Validation experiments demonstrate an exchange accuracy within ±2%v/v across the whole travel range, while fluid exchange efficiency was calculated for various use cases using CFD simulations. The Push2Pull syringe holder offers an accessible, open-source solution for precise fluid handling, for a material cost of less than $10.

The syringe holder exist in two sizes, for small syringes 1-10 mL (⌀6-16 mm) and for large syringes 5-60 mL (⌀12-30 mm). The small holder has a variable 1-5° angle between the syringes and the large holder has a fixed 0° or 10° between them. There is an assembly guide for each size and the selection guide tells you which parts to 3D print. The off-the-shelf parts needed, are give below.

Small Holder: 6 pcs - MR63 Sealed Ball Bearing, 3 x 6 x 2.5 mm 1 pc - M3 x 60 mm SS Socket Head Screw (20 mm thread) 1 pc - M3 x 20 mm SS Socket Head Screw 2 pcs - M3 x 16 mm SS Socket Head Screw 3 pcs - M3 SS Nyloc Nut 2 pcs - M3 SS Hex Nut 1 pc - M3 SS Flat Washer 1 pc - Compression Spring, 0.3 x 4 x 10 mm

Large Holders: 6 pcs - MR84 Sealed Ball Bearing, 4 x 8 x 3 mm 1 pc - BA4 Thrust Ball Bearing, 4 x 9 x 4 mm 1 pc - M4 x 60 mm SS Hex Head Bolt (>20 mm thread) 3 pcs - M4 x 25 mm SS Socket Head Screw 1 pc - M4 x 10 x 10 mm Blind Knob 3 pcs - M4 SS Nyloc Nut 1 pcs - M4 SS Flat Washer 1 pc - Compression Spring, 0.4 x 5 x 10 mm

Full article at HardwareX: https://doi.org/10.1016/j.ohx.2026.e00756

The Push2Pull syringe holder (Patent pending) is licensed under CC BY-NC-SA 4.0 and anyone is free to non-commercially redistribute, remix, and use the design by giving appropriate credit, while using and providing a link to the original license.