Hubs for medical devices

A mold system for making a medical device, comprising:

• a mold having a mold cavity for receiving a material;
• a first core pin having a first lumen-defining section located, or configured for placement, in the mold cavity;
• a second core pin having a second lumen-defining section located, or configured for placement, in the mold cavity;
• and
• a spacer tool having a lumen sized for accommodating a first tube when the first tube is in a fixed position with respect to the mold, wherein when the first tube is in the fixed position with respect to the mold, an end of the first tube is engaged with the first lumen-defining section of the first core pin,
• wherein the spacer tool comprises a first section configured for placement in the mold cavity of the mold, the first section of the spacer tool having a first outer cross-sectional dimension that is larger than an outer cross-sectional dimension of the first tube, wherein the first section of the spacer tool is in abutment against the second lumen-defining section of the second core pin, and
• wherein an end of the first section of the spacer tool is longitudinally located between an end of the first lumen-defining section of the first core pin and an end of the second lumen-defining section of the second core pin.