Can I insert two strands of 1.75mm plastic side by side into the 3Doodler pen?
No. The 3Doodler Create+ and PRO+ pens only work with 3mm plastic. Plastics cannot (and should not) be combined. As we have mentioned elsewhere, 3Doodler pens should only be used with 3Doodler-branded strands (which are specifically sized and configured for optimal use with 3Doodler pens). Use of other materials not approved by us may result in damage to your pen or injury to you, and will void your warranty.