@rbyeab
As Ed said . . . the parts required to complete your component set, IF AVAILABLE SEPARATELY, will cost you more than a complete kit.
The parts you show are for a ( Artisan ) Cigar Pen Kit . . . Craft Supplies USA sells those kits.
The parts you show are the top cap (finial), the clip, and an internal tube with coupler that screws into the cap that you show.
What you now need to complete the kit are the two pieces of brass tubing that constitute the primary structure of the pen, plus the nib end (pointed) and the center band. . There may be an additional coupler that mates the nib to one of the brass tubes. . The brass tubes required are classified as "10 mm" diameter because the drill size used to drill the blanks is a 10 mm drill bit. . I do not know the actual lengths of tubes.
Also required is a "twist action" mechanism to extend and retract the Parker-style refill ( also required ).
In addition, some other parts may be required (see the complete diagram linked below)
The tube that you show in your picture does NOT get glued into a blank. . Its purpose is to slide snugly over the twist mechanism which attaches to the lower "10 mm" tube's top end. . The tube you show has an attached coupler that screws into the cap that you show.
When replacing the refill, the top half of the pen pulls or twists off, thus exposing the twist mechanism which can be unscrewed to then expose the refill to be replaced.
A complete diagram showing ALL parts required can be viewed (and printed) here :
This PDF document also shows the exact sizes of the bushings required.
You can buy the complete kit at that source, or you can buy from other vendors as well, including ..... www . ExoticBlanks . com
or ..... www . penblanks . ca .....
Be aware that this particular component set that you show could be from any number of vendors. . This general style of kit has been around for many years and has been copied several times and remarketed with slight variations in the kit name. . There could be slight variations in the dimensions depending on the vendor who marketed.
If you want to cut your own brass tubes, you can buy 10-inch lengths of the "10 mm" brass tubes and cut your own according to the dimensions given in the last link I gave above. . . This design of pen is quite common and is quite forgiving to small variations in the brass tube lengths ( within reasonable tolerances ).
Good luck, and have fun !!!