Method for forming a transparent, one-piece, single layer timepiece component including a top surface and a bottom surface connected by an edge, said edge extending in the thickness of said component, characterized in that: - a first transparent, polymerisable moulding material is selected for making said component, said first material including, as a proportion of the total: ∘ a mixture of trimethylolpropane tri (methacrylate) and pentaerythrityl tetraacrylate: 50-97.5% ∘ bis (4-tert-butylcyclohexyl) peroxydicarbonate: 0.5-1.5% ∘ 1-benzoylcyclohexanol: 0.7-2.3% ∘ at least one additive 0-50%; - polymethylsiloxane is selected as the second moulding material, to make a flexible mould for moulding said first moulding material and to allow the removal thereof from the mould; - a plate is made having a contact surface which is the negative of said top surface; - a flexible female mould is made in said second moulding material, said female mould including: - a first contact surface forming a female mould of said bottom surface; - around said first contact surface, an edge including a first bearing surface arranged to cooperate in a complementary manner with said contact surface of said plate; - and a second bearing surface opposite said first surface; - an injection and degassing capillary network is made in said female mould; - said second bearing surface of said female mould is applied to a support plate; - at a distance from said first surface corresponding to the thickness required for said component, and exactly positioned in relation to said first surface, said plate is positioned with said contact surface thereof facing said first contact surface of said female mould, with said first bearing surface in sealed contact with said contact surface of said plate; - said first moulding material is injected through said injection capillary network, so as to completely fill with said first moulding material a cavity delimited by said contact surface of said plate, said first contact surface of said female mould and said edge in sealed abutment via the said first bearing surface thereof on said contact surface; - said first material injected into said cavity is left to polymerise until a said rigid component is obtained; - said plate and said support plate are moved away; - said component is removed from said flexible female mould by the deformation of said mould. - a first transparent, polymerisable moulding material is selected for making said component, said first material including, as a proportion of the total: ∘ a mixture of trimethylolpropane tri (methacrylate) and pentaerythrityl tetraacrylate: 50-97.5% ∘ bis (4-tert-butylcyclohexyl) peroxydicarbonate: 0.5-1.5% ∘ 1-benzoylcyclohexanol: 0.7-2.3% ∘ at least one additive 0-50%; ∘ a mixture of trimethylolpropane tri (methacrylate) and pentaerythrityl tetraacrylate: 50-97.5% ∘ bis (4-tert-butylcyclohexyl) peroxydicarbonate: 0.5-1.5% ∘ 1-benzoylcyclohexanol: 0.7-2.3% ∘ at least one additive 0-50%; - polymethylsiloxane is selected as the second moulding material, to make a flexible mould for moulding said first moulding material and to allow the removal thereof from the mould; - a plate is made having a contact surface which is the negative of said top surface; - a flexible female mould is made in said second moulding material, said female mould including: - a first contact surface forming a female mould of said bottom surface; - around said first contact surface, an edge including a first bearing surface arranged to cooperate in a complementary manner with said contact surface of said plate; - and a second bearing surface opposite said first surface; - a first contact surface forming a female mould of said bottom surface; - around said first contact surface, an edge including a first bearing surface arranged to cooperate in a complementary manner with said contact surface of said plate; - and a second bearing surface opposite said first surface; - an injection and degassing capillary network is made in said female mould; - said second bearing surface of said female mould is applied to a support plate; - at a distance from said first surface corresponding to the thickness required for said component, and exactly positioned in relation to said first surface, said plate is positioned with said contact surface thereof facing said first contact surface of said female mould, with said first bearing surface in sealed contact with said contact surface of said plate; - said first moulding material is injected through said injection capillary network, so as to completely fill with said first moulding material a cavity delimited by said contact surface of said plate, said first contact surface of said female mould and said edge in sealed abutment via the said first bearing surface thereof on said contact surface; - said first material injected into said cavity is left to polymerise until a said rigid component is obtained; - said plate and said support plate are moved away; - said component is removed from said flexible female mould by the deformation of said mould.