Convertible writing instrument assemblies are provided, including an outer barrel having a tapered nosecone with an aperture for a writing instrument tip and a grip portion, and an aperture for receiving an eraser or a push button therethrough, wherein the writing instrument assembly provides selective access to a volume defined by the outer barrel, and wherein the outer barrel and the volume are collectively configured to operably and interchangeably receive a mechanical pencil insert having the eraser and a retractable pen insert having the push button. Mechanical pencils and pens utilizing the convertible writing instrument assemblies are also provided, along with kits for providing such mechanical pencils and pens.

A mechanical pencil 1 includes a rotary member having a ball chuck 11, a rotation drive mechanism 30 having a rotary part 40 and driving the rotary part to rotate in one direction upon receiving a retracting motion in the axial direction due to writing pressure received by the lead clutched by the ball chuck and an advancing motion in the axial direction due to release of the writing pressure, and a cylindrical member 8 made of metal provided at one of the cylindrical barrel and the rotary member, the rotary member configured so as to rotate upon receiving rotational drive force of the rotary part whereby the lead clutched by the ball chuck rotates, the other of the cylindrical barrel and the rotary member slidingly contacting the surface of the cylindrical member whereby rotation of the rotary member due to the rotation drive mechanism is supported.

A multi-function writing instrument comprises a body extending in an axial direction and a radial direction, and having at least two writing elements arranged inside the body, each writing element comprising a writing head and a button, at least one button extending in the radial direction through a window and allowing the writing element to be moved between a retracted position in which the writing head is retracted into the body and a writing position in which the writing head projects from the body, and one of the writing elements being a leadholder system comprising a leadholder mechanism and a lead container, the button of the leadholder system comprising a lead-insertion channel extending in the axial direction.

A knocking-type writing instrument has a writing refill, such as a pencil lead or an ink cartridge, that is advanced by knocking a knocking member, and an eraser held by an eraser holder disposed at a rear part of the knocking member. When the writing instrument is inclined so that the eraser side faces downward, a control pin provided in the eraser holder and a movable stopper drop by their own weights along a sliding groove of the knocking member. When the control pin drops a predetermined distance and enters a circumferential locking groove provided at a rear end of the sliding groove, detachment of the control pin is prevented by the stopper, and the eraser holder is unable to retract to the inside of the knocking member. In this state, a radial projection on the control pin abuts a rear end face of the knocking holder, whereby the knocking member is locked and can no longer be knocked, and feeding of the writing refill is prevented.

An inductor core includes a magnetic main body having a pillar shape and comprised of a magnetic material. The magnetic main body includes an inclined portion including an inclined surface that constitutes an outer circumferential surface of a truncated cone having an outer diameter increasing from one end toward the other end; and a straight body portion that is coaxial with the inclined portion and includes an outer peripheral surface that constitutes an outer circumferential surface of a cylindrical column body extending from the other end toward the one end, the straight body portion being connected to the inclined portion. An arithmetic mean roughness Ra of an outer peripheral surface of the straight body portion located at or around the other end is smaller than an arithmetic mean roughness Ra of an outer peripheral surface of the straight body portion that is disposed at or around the inclined portion.

A multi-function writing instrument comprises a body extending in an axial direction, at least two writing elements arranged inside the body, each writing element comprising a writing head able to take up a retracted position in which the writing head is stowed in the body and a writing position in which the writing head protrudes from the body, one of the writing elements being a lead-holder system comprising a lead-holder mechanism and a lead container, the lead container comprising a side opening for inserting leads.

Provided is a self-made LED luminous floating oil pen, including an empty pen tube. One end of the empty pen tube is threadedly connected to a plastic shell, and the inner cavity of the empty pen tube is filled with a mineral oil. Two sides of the inner cavity of the empty pen tube are provided with LED lamp beads distributed at equal intervals, and floating action figures are arranged in the inner cavity of the empty pen tube. Glitter and hollow plastic balls are filled in the inner cavity of the empty pen tube.

The writing instrument includes a body, a nosecone, and an adapter. The body, nosecone, and adapter each include a generally hollow tubular shape and an inner surface, outer surface, first end, and second end. The first end of the adapter is coupled to the second end of the nosecone. The second end of the adapter is configured to slidably couple to the first end of the body. The writing instrument includes a writing element with a mounting end and a writing end. The mounting end of the writing element is removably coupled to a second end of the body. The adapter includes a track and the track includes a recessed channel in the outer surface of the adapter. The body includes at least one protrusion that extends inwards from the inner surface of the body. The protrusion slidably engages with the track of the adapter.

A multifunctional writing instrument comprising a body housing at least two writing elements, each writing element comprising a writing tip, a selection device configured to select one writing element from the at least two writing elements and a retraction device configured to move a selected writing element between a writing position in which the writing tip of the selected writing element protrudes from the body and a retracted position in which the writing tip of the selected writing element is retracted.

A pen includes a pen tube, a connection structure, a cap and an elastic unit. The pen tube includes a pen tube case and a thread portion provided at the pen tube case. The connection structure includes a main body, a corresponding thread portion and an elastic unit fastener. The corresponding thread fastener is located at the main body and is for joining with the thread portion. The elastic unit fastener is provided at the main body. The cap includes a cap case and an elastic unit corresponding fastener provided at the cap case. The two ends of the elastic unit are respectively fastened to the elastic unit fastener and the elastic unit corresponding fastener.