A method for assembling a shell section of a wind turbine blade, the method comprising: • providing a support, the support comprising a surface having a primary surface portion configured for supporting a first component and a secondary surface portion configured for supporting a second component, • providing a first joining device configurable between a first configuration wherein an attachment part of the first joining device is extending from the primary surface portion and a second configuration wherein the attachment part is retracted and do not extend from the primary surface portion, • providing a first component comprising an inner surface, an outer surface, a first primary end and a first primary joint part along the first primary end, wherein the first primary joint part comprises a first primary joint surface facing opposite the inner surface of the first component, • providing a second component comprising an inner surface, an outer surface, a second end, a second joint part along the second end, wherein the second joint part comprises a second joint surface facing opposite the outer surface of the second component, • arranging the second component on the secondary surface portion such that the outer surface of the second component is facing the secondary surface portion, • arranging the first component on the primary surface portion such that the outer surface of the first component is facing the primary surface portion, and such that the first primary joint surface of the first component is facing the second joint surface of the second component, • attaching the attachment part to the outer surface of the first component, wherein the method comprises applying a force to the first component to force the outer surface of the first component towards the primary surface portion and the first primary joint surface towards the second joint surface, wherein applying the force to the first component comprises transitioning the first joining device from the first configuration towards the second configuration to apply the force to the first component. • providing a support, the support comprising a surface having a primary surface portion configured for supporting a first component and a secondary surface portion configured for supporting a second component, • providing a first joining device configurable between a first configuration wherein an attachment part of the first joining device is extending from the primary surface portion and a second configuration wherein the attachment part is retracted and do not extend from the primary surface portion, • providing a first component comprising an inner surface, an outer surface, a first primary end and a first primary joint part along the first primary end, • providing a second component comprising an inner surface, an outer surface, a second end, a second joint part along the second end, wherein the second joint part comprises a second joint surface facing opposite the outer surface of the second component, • arranging the second component on the secondary surface portion such that the outer surface of the second component is facing the secondary surface portion, • arranging the first component on the primary surface portion such that the outer surface of the first component is facing the primary surface portion, and such that the first primary joint surface of the first component is facing the second joint surface of the second component, • attaching the attachment part to the outer surface of the first component, wherein the method comprises applying a force to the first component to force the outer surface of the first component towards the primary surface portion and the first primary joint surface towards the second joint surface, wherein applying the force to the first component comprises transitioning the first joining device from the first configuration towards the second configuration to apply the force to the first component.