Some Key Reference information form the the D4 Delta Notebook:

Sewing the Delta2p Bed instructions

Sewing the Delta2p Fly instructions

Delta2p Reference:

Delta3p Reference:

more Delta1p Reference:

35mm*1.5mm to 30mm tube D4 Joiner STEP file

D4 Joiner Files: 

CAD/CAM STEP FILES (.step format) available on request (open source with attribution). Many sizes available.